1918a2 bar manual
Transcription
1918a2 bar manual
DEPARTMENT OF THE ARMY T ECHN I CAL MAN UAL lfTVl (ij)o0)111111o11 UlMJ Q!J L'£U UU U (FORMERLY Til 9-1211) DEPARTMENT OF THE AIRiflnl1111\Y.V/0)o~o0)o110)0) FORCE TECHNICAL ORDER Ul!!J UUU\1~ QJJ ~ UL'£{£ FIELD MAINTENANCE CAL.. 30 BROWNING AUTOl\1ATIC RIFLE Ml918A2 DEPARTMENTS OF THE ARMY AND THE AIR FORCE FEBRUARY 1957 This manual is correct to 22 J anuary 1957 *TM 9- 2111-1 TO 11W3-5-3-122 1\I A ' UAL l No . 9- 2111- 1 TECEINLCAL T ECIINI CAL ORDER No. 11W3- 5- 3- 122 DEPARTl\IENTS OF THE ARl\IY AND THE AIR FOR 'E W ASH L'\ GTOX 25, D. C ., /8 Febmary 1957 CAL. .30 BROWNING AUTOMATIC RIFLE Ml918A2 C' II AI'TER , 't~1· t ion C HAPTER 'crtion CHAPTER l N TRODUC'T I0:\1' __ _ _________ ______ ___ __ ____ __ _ I. l. ll. 2. 3. I. II. III. IV. Parng-raJ1h~ Pn!!f"' 1- 3 4,5 PARTS, SPE 'l AL TOOLS. A~D EQlfiPl\IENT FOR FIELD MAlNTENAXCE_ ______________ _ I N. PECTIONS _____ ___________________________ _ 6- 9 GeneraL __________________ __________________ __ _ Inspection of materiel in hands of t roops ___________ _ Preembarkation inspection _____________________ __ _ I nsp ection of materi el received in ordnance shops ___ _ 7 1L 10- 12 13-27 2 ,29 30,3 1 lL J:2 4. REPAIR ____________________ ________________ __ _ GeneraL _______ _____ ____ ______________________ _ II. Trigger guard assembly ___________________ _______ _ lll . Barrel and reC"eiver group ________________________ _ IV. Bolt group _________ _____ _______________________ _ v. Butt stock, bufl'er, and actua to r grou p ____________ _ lideand pisto n group ____ _______ ____ _________ __ _ VI. 32- 43 44- 49 50- 53 54-5 59- 62 63-66 VII. Gas cylinder and forearm group _-- -------- - - ------ 67- 70 VIII. Rear sight assemb ly ____ -------- _____________ ---_ 71- 75 IX. l\l agazine assembly __________ _____ ___________ ___ _ 76-79 X. Bipod assembly ________________________________ _ Q-4 'a.l. .30 jointed cleanin g rocll\1L _________________ _ 5, 6 XI. 5. F INAL I N~PE "riO N _________________________ _ 87, 8 C HAPTER APPENDIX. REFERE. CE -------- -- ----------------------- , 'ettion '2 :2 c:eneral _______________________________________ _ D e. r ription and data ____________________________ _ I. IxD EX _ __ ______________________________________ _____ _________ _ 3 18 1\) 21 21 25 32 <14 ·16 52 56 63 66 68 6 71 72 75 *This manual supersedes TM 9-1211, 15 September 1947, and those portions of TB ORD 507, 1 April 1953, and TB ORD 587, 20 December 1954, pertaining to the equipm ent described in this manual. AGO 4471B-:'-ltLr. 3. CHAPTER 1 INTRODUCTION Section I. 1. GENERAL Scope a. These instructions are published for the use of personnel responsible for field maintenance of t his materiel. They contain information on maintenance which is beyond the scope of the tools, equipment, or supplies normally available t o using organizat ion . This publication doe. not contain information which i intended primarily for the using organization sin ce uch information is avai lable to ordnance maintenance per ·onnel in FM 23- 15. b. This publication contains a description of and procedures for removal, di a. sembly, inspection, repair and assembly of the cal. .30 Browning automatic rille M1918A2. The appendix contain s a list of current references, including supply and technical manuals form s, and other available publications applicable to the cal. .30 Browning automatic rille 11918A2. c. FM 23-15 contains operating and lubricating instructions for t he materiel and all maintenance operation allocated to using organizations in performing maintenance work within their scope. d. This publication differ from TM 9- 1211, a follow : (1) Adds information on(a) Inspections. (b) Cal. .30 jointed cleaning rod n. (2) Revises information on(a) Field maintenan ce allocation. (b) Forms, records, and r ports. (c) Parts, special tools, and equipm ent for field maintenance. (d) Repair of the weapon. Field Maintenance Allocation The publication of instructions for complete disas embly is not to be construed as aut hority for the perfo rmance by field maintenance units of tho e fllllctions which have been restricted to depot shops and arsenals. In general, the pre cribed maintenance responsibilities will apply as reflected in the allocation of maintenance parts listed in the appropriate columns of ORD 8 S JL A-4. Instructions for depot maintenance are to b u eel by maintenance companies in the field only when the tactical ituation makes the repair function imperative. Provision of parts listed in the depot guide column of ORD 8 supply manual will be made to field maintenance only when the maintenance to be performed has been certified by a respon ible officer of the req uisitioning organization . Forms, Records, and Reports a. General. Responsibi li ty for the proper execution of forms, records, and reports rests upon the officers of all units maintaining t his equipment. However , the value of accurate records must be fully appreciated by all persons respon ible for compilation maintenance, and use. Records, reports, and a ut horized forms are normally utilized to indicate the type, quantity, and condition of materiel to be in pected, repaired, or used in repair. Properly executed forms convey authorization and serve as records for repair or replacement of materiel in the hands of troops and for delivery of materiel requiring further repair to ordnance shops. The forms, record , and reports e tablish the work required the progress of the work within the shops, and the status of the materiel upon completion of its repair. b. Authorized Forms. The forms generally applicable t o units maintaining these weapons are li ted io the appendix. For a complete listing of all forms, see DA Pam 310- 2. For instructions on u of t hese forms, refer to FM 9- 10. c. Field Report of Accidents. (1) I nju1·y to ]Jersonnel or damage to materiel. The reports necessary to comply with t he requirements of the Army afety program are pre cribed in detail in SR 385- 10- 40. These report are required whenever accidents involving inj w-y to personnel or dan1age to materiel occw-. (2) Ammunition. ·w henever an accident or malfunction involving the use of ammunition occurs, firing of t he lot which malfwlctions will be immecliately discontinued. In addition to any applicable reports required in (1) abov , details of the accident or malfllllction will be reported as prescribed in SR 700--45-6 . d. Report of nsatisf actory Eqt~iprnent or lvfaterials. Any deficiencies detected in the equipment covered herein, which occur under t he circum stances inclicated in AR 700- 38 should be immediately reported in accordance with the applicable instructions in cited regulation. Section II. DESCRIPTION AND DATA 2. 2 AGO 4471B 4. Description (figs . 1 and 2) a. The cal. .30 Browning automatic rifle .r 1J918A2 is an air-cooled, gas-operated , magazine-fed, shoulder-type weapon. It i primarily composed of a barrel and receiver group, trigger guard assembly, gas cylinder and forearm group, slide and piston group, rear sight assembly, buffer group, hinged butt plate assembly, magazine a sembly, bipod assembly, and bolt group. b. The trigger guard a .·embly, located on the bottom of the receiver, acts as a housing for the trigger mechanism, ejector, magazine catch, and cyclic change lever. AGO 4471B 3 0 a.. ~ "'a-.., "',..., 0 a.. ~ ...:;; "' 53 ..:::. -"' -~ ;.. ~ (;, <b T "> <>2 -. -:::"' --: ..<:::. . ..... g ~<:: -~ '"' , ::; .s 0 ~ "i tt"" 4 AGO H71B AGO 4471B 5 c. On the front of the receiver, just below the barrel, is the gas cylinder and forearm group, within which the slide and piston group reciprocates, actuated by gas pressure and the recoil spring. d. The rear sight assembly is located on the top of the receiver just forward of the butt stock. e. Inside t he butt stock is the buffer tube , which houses the buffer group, composed of alternate cones and cups, and the actuator which, combined with the actuator spring, operates in the passage formed by t he actuator tube. f. The rear end of the stock is closed by the hinged butt plate assembly. g. The magazine assembly, located on the bottom of the receiver towards the front, holds 20 rounds. h. The bipod assembly is mounted with the fl ash hider and bipod bearing on the front of the barrel. i . The bolt group, housing the firing pin and extractor, operates inside the receiver . j. The rifle is furnished with a cyclic rate mechanism housed in the butt stock with a trigger guard mechanism . The cycli c rate mechanism allows two rates of automatic fire, 550 rounds per minute (normal cyclic rate) and 350 rounds per minute (slow cyclic rate) . 5. Weight (complete with bipod a nd magazine assemblies) ______ ______________ ______ l 9.4lb Weight (less bipod) ___ _______ ______ _____ 17lb Weight of bipod assem bly ___ ___ ___________ 2.38 lb Weight of magazine assembly __________ __ 0.44lb Weight of moving part s ___________ _____ _ 2.25lb Weight of barrel_ _________ _____ ____ ___ _ 3.65 lb Length of rifl e ____ __ ___ _____ _____ _____ _ 47.8 in. Length of barrel_ ___ __ __ _________ _____ _ 24.07 in. Length of rifling ___ ___ __ _______________ 71.1 cal. (21.41 in .) Rate of fu·e _____ _______ ______ ___ ___ ___ _ Cooling system ___ __ _____ __ _________ __ _ Sight radius ________ ___ _____ _____ _____ _ Trigger pull _____________ ____ ____ ______ Ammunition types ____ __ ____ _____ ___ ___ 6 PARTS, SPECIAL TOOLS, AND EQUIPMENT FOR FIELD MAINTENANCE 6. General Tools and equipment and maintenance part over and a bove those available to the using orga nization are supplied to ordnance fi eld maintenance units for maintaining a nd repairing t he materiel. 7. Parts Maintenance pa rts are listed in ORD 8 S L A-4, which i:s the authority for requisit ioning replacements. 8. Common Tools and Equipment Standard and commonly used tools and equipment having general application to this materiel are listed in ORD 6 SNL's J - 8 Section 6 and J- 10, Section 2, and are authorized by TA and TOE. 9. Special Tools and Equipment The special tools and equipment tabulated in table I are li:sted in ORD 6 St-.TL J- 12. This tabulation contains only those special tools and eq uipment necessary to perform the operations described in this publication, is included for information only, and is not to be used as a basis for req uisitions. Tabulated Data Rifling: umber of grooves ___ ____ _____ _____ Right-hand ed twist (o ne t urn in ) _____ Depth of grooves __ __ ______________ Cross-sectional a rea of bore ______________ T ype of mechanism_ _ _ ______ _____ ___ __ _ Feeding device ___ ____ __ _____ ___________ Capacity of feeding device ______________ CHAPTER 2 Note. Special tool sets in ORO 6 SNL J- 12, in audition lo ~pcciaJ tools, a l o con tain sta ndard a nd co mmonl y used tools and equipm ent specifica lly app licable to this materiel. Table I . Special Tools and Eqtt-ipmenl f or Field Maintenauce 4 33.3 cal. (10 in .) 0.0040 in. 0.0740 sq in. gas-operated magazine 20 rds 500 to 650 rds per min (fast a utom atic) { 300 to 450 rd s per· min (slow a utom atic) air 31.125 in. 10 lb max; 6 lb min ball; AP; tracer AGO 4471B R eferences Identify ing No. Item F ig. Usc P ar. 50a(2) bbl 6316006 4, 10 cleaning, BRUSH, chamber, cal. .30, Ml. EXTRACTOR, ruptw·ed cartridge case, cal. .30, Mk II. FILLER, magaz ine, cal. .30. 6528362 4 5507912 4 --- - - - - -- - -- For extractiug ruptured cartridges. 5507913 4 --------- --- BLOCK, vise, holding, S. AGO 4471B T o provide positive reten tion a ud prevent di stortion of barrel wh en clamped in vise. -- - - - ------- To clean the cha mber. T o aiel in loadjx1g magazine ra pid ly. 7 'l'able I. Special 'l'ool" and Eq1tipment for Field Maintenance- continued H cfcr·t"nc·es IdcntifyiUJ< , _ Hom No. _ __ / Fil(. _ __ _ _ Par. I I Use --------- 1---------------GAGE, breech bore, cal. .30. 556-13~:3 3 J8t.., 5 l a(2J(c J, 88 GAGE, heads pace, cal. .:30, 1.9.J.O in. i3 199-14 3, 5 27b( 1), 88 headspacc, GAGE, cal. .30, 1.!J50 in. 7:3 19H5-I :3, 5 27b(2), 88 GAGE, plug, NO GO, gas cyl, cal. .30, dia 0.053. GAGE, ring, OGO, piston dia, cal. .30, clia 0.-!94. REFLECTOR, bbl, cal .. 30. "07720-1 3, 2 2:3.f, 68b(3 ), 8 ROLL, tool, canvas empty, i\Il2. TOOL, a linement, buffer tube, cal. .30. Composed of: PARALLEL. ____ PLUG ____ _____ _ SPACER ________ TOOL, clean ing, gas 5077201 3, 25 20b, 64c(2 J, 88 726578 -l 51a(2l (b) 631G00 1 -!, 7ll3327 7113326 7113328 4, 16 .J , ](j -!, 13, 20 3, 27 53a(2) 53a(2) 50r(5), 53a(2) 23.f, 65a, 68b(2) -! G7b(-l), 69c, 726 211 TOOL, comb _______ _ 72G6-!50 ](j 53a(:2) 70a 8 CAL. .30 PISTON DIA NO GO RING GAGE-507720 1 To provide a ligh t reflecting surface for vis ual inspection of rifle bore without removing th e barrel from re cc ivcr. CAL .30 BREECH BORE . GAGE-5564343 GAS• CYLINDER CLEANING TOOL7268211 1.940-IN. CAL .30 HEADSPACE GAGE7319944 G5U7:38!J c~· lind er. WRENCH single, open end, receiver and bbl. To gage the lands at the breech end of the bar rei to detcrn:tine its serviceability. To gage t he distance be tween the ~houlder o the chn.m l or and the face of the bolt. To gage the di stance be tween the shou lder o the chamber and the face of the bolt. To gage the in ide cliam eter of the gas cyl inder. To gage the diameter of the piston. G:316005 4, 10 50a(2) To position the buffc tube in receiver so tha one of eigh t grooves ir bead of buffer tube lie centrally horizonta \l"ith top of receiver. CAL. .30 GAS CYLINDER NO GO PLUG GAGE-5077204 1.950-IN. CAL. .30 HEADSPACE GAGE7319954 RA PD 917520 Figure 3. SJJeciol tools for Jield maintenance. To remove carbon from gas cylinder and face of piston. To assemble and disas semble weapon (F:\ 23- 15) . To remove receiver from barrel. AGO 4471B AGO 4471B 9 CHAPTER 3 INSPECTIONS aa.. ~ Section I. GENERAL 10. Scope Paragraphs 10 through 31 provide specific instructions for the technical inspection by ordnance maintenance personnel of materiel either in the hands of troops or when received for repair in ordnance shops. It also briefly describes the in-proce s inspection of materiel during repair and the final inspection after repair has been completed . Troubleshooting information is incorporated wherever applicable as a normal phase of inspection. 11. Purpose of Inspections Inspections are made for the purposes of (1) determining the condition of an item as to serviceability, (2) recognizing conditions that would cause failure, (3) assuring proper application of maintenance policies at prescribed levels, and (4) determining the ability of a unit to accomplish its maintenance and supply mis. ·ions. 12. Categories of Inspection In general, five categories of inspection are performed by ordnance maintenance personnel. a. Overall I nspection. This is a periodic overall inspection performed by a contact party on materiel in the hands of troops and an inspection performed by maintenance company personnel when materiel is evacuated to the ordnance company . The inspection of evacuated materiel is more thorough and includes check and repair of minor points that should not be required in the inspection performed by a contact party. b. Preembcakation I nspection. This inspection is conducted on materiel in alerted units sched uled for oversea duty, to insure that such materiel will not become unserviceable or n~orn out in a relatively short t ime. It prescribes a higher percentage of remaining usable life in serviceable materiel to meet a specific need beyond minimum serviceability. c. I n-P1·ocess I nspections. These are inspections performed in the process of repairing the materiel. This is to insm e that all parts conform to the prescribed standards, that the workmanship is in accordance with approved methods and procedures, and that defi ciencies not disclosed 1:: r the preliminary inspection are found and corrected. Detailed inst ructio s are contained in chapter 4. d. Final I nspection. This is an acceptance inspection performed by a final inspector after repair has been completed, to insure that the materiel is acceptable for return to user according to the standards establi heel . Detailed instructions are contained in chapter 5. 10 AGO 447lB AGO 4471B 11 e. Spot-Check In specti on. This is a periodic overall inspection performed on on ly a percent age of t he materiel in each unit, to determin e the adequacy and effectiveness of organizational and field maintenance. Section II. 13. INSPECTION OF MATERIEL IN HANDS OF TROOPS Precautions Before starting a t echni cal inspection, be sure t o clear t he weapon. Do not touch the trigger until the weapon has been cleared . Inspect the bore and hamber to insure that they are empty and check to see that no ammunition is in position to be in troduced. Avoid hav ing live ammunit ion in the vicini ty of the work. 14. General a. R efer toT 1 9- 1100 for responsibilities and fundamental duties of in pecting personnel, the neces ary notice and preparations t o be made, forms to be used, and general procedmes and methods to be followed by in pectors. Mat eriel t o be inspected includes organizational spare parts and equipment and the stocks of cleaning and preserving materi als. b. Check to see that the weapon ha been cleaned of all corrosionprevent ive compound, grease, excessive oil , dirt, or foreign matter whi ch might interfere with proper fun ctioni ng or obscure t he true condi tion of the parts. c. f ake an overall in pection of t he weapon for general appearance, condit ion, operation, and manual fun ctioning. U. e dummy or drill car tridge . d . D etermi ne serviceabili ty, i. e., the degree of serviceability, completene , and reacliness for immediate use, with pecial reference to safe and proper functioning of the materi el. If t he ma teriel is found serviceable it "ill be ont inued in service. In the event it is found un ervi ea ble or incipient failmes are discl o eel , t he defi ciencies will be corrected on t he pot or advice given a: to corrective measm es when applicable, or, if nece ary, the materiel \\ill be tagged for delivery to and repair by, ordnance maintenance per onnel. e. Determine causes of mechani cal and ftmctional difficulties that troops may be experi encing and check for apparent re ults of lack of lrno,Yleclge mi inform ati on neglect , improper handling and storage, secmity , and preservation. f. Check on a pplication of all urgen t modifications, and if any unauthOL·ized alterations have been made, or if work beyond the a uthorized scope of the unit is bein g attempted 'l:WO ORD A4- W6 which provides the rifle with the late:t gas cylinder assembly is considered mandatory; however, a] o check DA P am 310- 4 and the current modification \\"Ork order file for any additional work orders promulgated ubsequent to t his printing. 12 AG O 4<171 B g. In -true!; the using personnel in proper preventive-maintenan ce procedmes where fow1d in adequate. h. Check on completene s of the organizational maintenance allowan ces and procedures for obtaining repleni hments. i . Satisfactory metal fini shes for weapon s range from dense black to medium light gray. 'ertain smal l a rm weapons are manufactured with an unusual ·hade of neut ral gray fini h. Since t h is fini sh (gray zin c phosph ate) is an accepted D epartment of t he Army standard , t hese weapons will not be reject ed by in pec tors or t roop for this condition. Rigid restri ctions on shiny metal smfaces \vil1 not be carried to an extreme. A "·orn surface is obj ectionable from the standpoint of visibility when it is capa ble of reflectin g light, ome,Yha t as a mirror does. Check to see t hat all rear sigh ts have a dull black or gray fini h on all smfaces. .f. Wooden components must not be cracked in such a way as to interfere with the structw-al strength. Surface cracks bruises, or dents that do not affect t heir strength hould not cau ·e rejection. k. Ligh t pit ting of the barrel, even t hough plainly visible, is not cause for rejecting a weapon. I t does not affect t he accuracy materi ally, but i · a disadvan tage because it interferes wit h subsequent cleanings. A barrel that is Ulliformly pitted out wit h the edges of the lands sharp is accepta ble, provided the breech bore readin g of the barrel is ~atisfactory . Only t ho e barrel ho\Ying developed pits or pits cutting int o the la nd are unsatisfactory . Pits in the chamber large enough to cause extraction difficulties \viii be cau e for rejection. Ringed bore or bores ringed sufficient ly to bulge t he out. ide surface a re cause for rejection. l. Loosene. and play in uch components as sigh ts, gas cylinders, etc., may be cau. e for rejection. In many ca e , hO\Yever, the importance of such defects is exaggerated. Loo. ene a nd play must be considera ble to affect t he accm acy of a weapon beyond it natural eli persian . All weapons, especially aut om ati c guns, must have play between working components t o permit them to operate in localities where sand and dust are prevalent . A "' eapon may be completely useless if its working parts are fit ted 1\·ith insufficien t clearan ce. . m . Minor defects in metal components do not normally affect t heir being accept ab le. Sera ches and tool m ark · on barrels a re ordin arily of no importance. 15 . Rifle a. Hand-operate and check assemblies and parts for functioning and smoot hne s of operation. b. Inspect fit of m agazine in receiver and functioning of magazine cat ch and catch release with magazine. c. Using magazine and dwnmy cart ridges, test the loacling function of bolt and flm ctioning of the extractor and t he ejector. "\\ Then inspecting, use a sen r. il'eable magazine, as a worn retaining lug on t he magazine may allow mag .zine to drop , thus affecting the feed fun ction of t he bolt. AGO 4471 B 13 d. Inspeet locking action of bolt lock and bolt. e. Fire several rounds of service ammLmition, and examine primers of fired casings. If primer shows indications of being set back in firing pin hole of bolt, due to an enlarged fi ring pin h ole or re essive weat· of bolt face, replace the bolt. Warnin g: Test-fire when and where conditions permit, considering safety and expediency. 16. SIGHTS a. Check front sight base for looseness on the barrel, and check blade for looseness in the base. b. B lade must be straight and top of the blade square and properly darkened. c. In ·pect rear sight base for looseness on receiver. d. Inspect windage scale for looseness on base. e. Check spring for functioning. f. Inspect fun ctioning of elevat ing :>crew and leaf with sli de. Both must operate freely a nd retain setting . g. Windage knob will turn freely by hanrl and retain set. An acceptable dull finish is required on all parts. 17. Bipod Group a. Inspect bipod assembly for proper fit on flash hider bearing. b. Inspect bipod assembly for looseness on barrel. c. Inspect for missing or broken friction washer an d sight cover. d. Sliding legs will move readily to any position and wil l be locked and held by the bipod leg thumbscrews. 18. Note . checks. Barrel and Receiver Group Weapon must be field-stripped (FM 23-15) to perform pertinent gage a. Inspect headspace as described in paragraph 27. b. Check breech bore dim ension, using breech bore gage 556-±3-±3 (fig . 3). Insert the gage into the chamber. Looking through the ejection port and using the calibrated scale of the gage, read indi cation that appears just flush 'i\rith the rear face of the barrel. It should be 0.3 10 in ch or less. c. Inspect receiver for wear, burs, rust, and foreign matter. d. Inspect for loose bolt supports. e. Inspect bolt lock recess in top of receiver. Check especiall y where lock seats when bolt is locked . Burs here will affect headspace. f . Inspect operating handle for functioning and free movement in slideways. Inspect plunger for free movement and spring tension. g. Top plate should not be loose and a drive fit is required. 14 AGO 4471B 19. Bolt Group a. Inspect firing pin hole for out-of-round. It should be approximately three thirty-seconds inch. c. Check firing pin for broken point, wear, bms, and fracture. d. Remove extractor. Check spring for set or fracture, and check lips of extractor for wear. e. Check bolt link and lock for excessive wear, burs, and galling. Check holes for out-of-row1d. b. Check firing pin protrusion. 20. Slide and Piston Group a. Check fit between piston and slide. b. Total endplay of piston should approximate one-eighth inch in any direction and face of piston must not strike gas cylinder body when slide is in fully forward position. Gage piston, using NO GO gage 5077201 (fig. 3) . Piston h ead should not enter gage. To gage, first clean piston thoroughly of all carbon and fouling, and determine that surfaces of head ring are smooth and polished. Wipe piston head and gage with a slightly oiled doth and try to pass gage over piston head . (Only light pressure should be exerted on gage.) c. Inspect slide for burs, deformation, galling, or battered rear end. d. Check hammer pin hole for out -of-round . 21. Trigger Guard Assembly a. Check functioning by hand operation. b. Check change lever for movement in all po:;ition.· a ucl a bility to retain setting. c. 'heck ejector for bw·s fracture , or clefonnat,iou. ct. Check all springs for tension and set. e. Check magazine release and catch for proper furtctioning . 22 . Buffer and Actuator Group a. Check actuator for free movement in actuator tube. b. Check actuator spring for kinks, rust, and free length. c. Check buffer head assembly for burs, missing key , and sear release for free movement and correct assembly. Check cones a nd cups for set and proper assembly . 23 . Gas Cylinder Group a. Inspect gas cylinder for dents, cracks, deformat ion, and distortion. b. Check gas port in the gas cylinder body to be sw·e it is free of carbon or other foreign matter. c. Check gas cylinder body for burred or· stripped threads. AGO 4471B 15 d. Check the three ga ports in the gas regulator for carbon or other foreign matter. e. Be sure that dust ·bield is present. f. Inspect, gas cylinder body for wear, using gas cylinder gage 507720± (fig. 3). This is a N 0 GO gag and boule! not enter the gas cylinder body. Before gaging t he cylinder clean thoroughly to remove all carbon depo its and foreign matter, using ga cylinder cleaning tool 7268211 (fig. 4). Use crocus cloth to polish , and if nece ·sary, wipe cylinder and gage with a slightly oiled cloth and try to insert gage into cylinder. If the gage enters, it is unserviceable. (Only light pre ure should be exerted on gage.) 24. 26. Equipment a. Make lu·e all spare parts and equ.i pm ent, are on hand and in good eonclition. b. Slings will be compl 'te a semblies with keepers, frog·, and hooks attached. Leather sling wi ll be .·oft and pliable. When the sling is bent double over a l -inch rolU1cl bar, there should be no cracking of the leather. Leather slings will not be issued when the pre ·ent supply is dep leted. Web lings wi 11 not be rotted or baclly tainecl . Special attention should be given to the point at which metal is attached, to see that rust has not weakened the sling. lightly soiled web slings may be crubbed with a mild ' ' o. However, care should be taken to preserve the olive-dmb colo'· Stock and Forearm Grou p a. Butt plate 11-ill fit properly and scre11·s will not be stripped or have mutilated beads. b. Butt swivel ll'ill be secme, screws \\ill not be mutilated, and wivel screw will be tight and taked. c. Butt stocks will be checked for warping loose fit, and crack . d. Forearm will be in ·pected in accordance with instructions in paragraph 14j. 27. Headspace b. In testing trigger pllll of rifles, the inspector will use two weight , one of 6 pounds and one of 10 pollnds. c. Check to insure that the change lever is set at the A or F position and that the rifle is cocked . Rest the trigger "·eight on the floor or ground, and insert the hook of trigger weight wire through the trigger guard body bow to bear on the trigger, so that pressme is applied onequarter inch from the lower end or tip of trigger. With the barrel of the rifle held at a 30° angle to the vertical, carefully rai e the weight from t he floor. If the 6-pound weight pulls or the 10-pound weight fails to pull the trigger to rel ease the slide, correct (par. ±6e). Exercise care during the test to determine that the wire ontacts the trigger only bat it does not rub against the trigger guard body or stock, and tha wire and axis of bore are parallel and perpendicular. a. Geneml. (1) Definition. Headspace 01 ' cal. .30 Brmvning automatic rifle l\l1918A2 is the clistance between the shoulder of the chamber and the face of the bolt when the bolt is in " locked position. " (2) E.f)'ect of heaclspace on operation. If heaclspace is insufficient, the bolt does not fu lly lock behind the cartridge IYithout being forced. If headspace is exce. sive, the cartridge ha too much play in the chamber when the bolt i · locked behind it. Either conclition i liD afe. (3) Cause of variation in heaclspace. A· component parts of the rifie are manufactm d to close tolerances and headspaee is carefully checked at manufacture, a variation usually i due to wear, cau ing exces ·iv head pace to develop. However, assembly of parts with maximum tolerances results in either excessive or in suffi cient headspace. Exces ive heaclspace due to wear is caused by advanced chamber shoulder in the barrel, worn face of bolt, 1vorn locking boulder of bolt lock or worn locking reces in receiver. b. Gaging Headspace (fig. 5). Headspace is gaged with the firing pin and extractor removed from the bolt, reco il spring and gllicle remov cJ from the slide and piston group, operating handle removed from the receiver, and the trigger guard a· ·embly removed from the rifle. With the inspector's bore reflector, examine the chamber to mak certain that it is clean. Place the bolt a sembly (minus firing pin and extractor), with bolt link assembled, in the receiver. Then install the slide and piston group (min us spring and guide), and fit the hammer into its seat in .!ide and in. ert hamm r pin. Work the slide back and forth several times by hand to il1sUJ'e that the part~; are co rrectly as embled. In tall the ga. · cylinder and forearm group and lock it in position with ga cylinder retaining pin. \Yith slide pu heel fully fonmrd note the relative position of the hamm er pin with reference to the fonmrcl part of its ·lot inside of. 16 AGO 4471B 25 . Trigger Pull a. Test trigger pull for smoothness and pre sm e exerted. Trigger pull should be clean, without creep, and smooth in action. The for ·e exerted to relea. e slide is no le than 6 pound , nor more than 10 pow1ds. If the pull i rough, not within pecified limit or excessive creep i present, check for 1vear or bw·s on ear and slide notch or for interference between trigger and housing. ole. The word " creep" is in terpreted to mean any pei·ceptiblc movement in the lrigger pull bet\\'een the time the slack is taken up and the !ide is relea ed, with pressure applied at a uniform rate of increase over a period of not les than 10 seconds. AGO 4471B 17 receiver. It will be found that there is a clearance of from one thirtysecond to three sixty-fourths inch between the hammer pin and t he forward part of the slot. This position of the hammer pin is referred to as the "locked position. " POSI T ION OF HAMMER PIN WITH HEAD SPACE GAGE-7319954 IN CHAMBER SHOULD NOT BE LESS THAN 3/8 INCH FROM "LOCKED POSITION " POSITION OF HAMMER PIN WHEN IN "LOCKED POSI TION" WITH HEADSPACE GAGE-7319944 IN CHAMBER SHOULD BE FROM 1/32 TO 3/64 INCH 29. Examine all spare parts, tools, and equipment for completeness and serviceability. Rep lace any defective items. It is not normally necessary to inspect items in sealed packages, siuce they have been inspected for serviceabili ty prior to packaging and dW'iug ' torage. Section IV. 30. l /32 IN. TO 3/64 IN Organizational Spare Parts, Tools, and Equipment INSPECTION OF MATERIEL RECEIVED IN ORDNANCE SHOPS General A techni caJ inspection imilar to that in paragraphs lei: through 27 i:.; performed. In addition, the e:deut of repa.irs necessary is determiuecl and an estimate is made of the parts required. A troubleshooting iuspection i performed, as necessary, to localize malfunction and apply corrective measmes. 31. RA PD 909308 Fig ure 5 . Gaging heads pace. Troubleshooting Table II li. ts mali'unction. , their probable causes and proposed corrective actions. For troubleshooting information " 'ithin the scope of organizational maintenance, see FJ\I 23- 15. (1) JYfinimum headspace. To test for minimLm1 headspace, place the 1.9-±0-inch headspace gage 73199H (fig. 3) in the chamber and move the slide forward. Note the po ition of the hammer pin . It should be in the locked position (fig. 5) . If the hammer pin is in the locked position, the minimum headspace is correct. If the hammer pin i. · stopped before reachil:tg the locked position, t he headspace is insufficient and should be corrected by depot maintenance. Note. Never use force again t the gage to obtain locked position . (2) Maximwn headspace. To test for maximLLm heaclspace, place the 1.950-inch headspace gage 7319954 (fig. 3) in the chamber and move the slide forward until stopped by the gage. Note position of hammer pin. It should be not less than three-eighths inch from the locked position (fig. 5). If the hammer pin is not stopped on or before it i · in tb.is position, the headspace i. excessive and should be corrected by depot maintenance. Section Ill. 28. PREEMBARKA TION INSPECTION Rifle a. Proceed as in paragraphs 13 through 27 and in b and c below. b. Do not reject the rifle for oversea use unl ess exterior parts have a distinct shine; also, bright rear sights \"Vi ii not be permitted on weapons for oversea u. e. r.. The breech bore dimension (par. l8b) should be 0.306 inch or less. 18 AGO 4471B Table II. Malfunction Troubleshooting Probable causes Correeti \"e action Failure to feed _____ _____ _ Dirty or dented magazine body. \Yeak or broken magazine spring. \\' orn or broken magaziuc catc h. Damaged sear or sea r Failu re or slide to cock no tc h in lide. Broken sear spring __ ____ _ R eplace magazine (pa rs. 76 anJ 79) . Replace magazine (pars. 76 and 79). Heplace magaz ine ca tch (par' . H an d -+7 ). Replace slid e or sear (pars. -+.J a nd -+7 ). R eplace sear -pring (pars. -lA and 47 ) . Clean a nd remov.e bur~ (pars. 44 a nd .J7 l. Correct (pars. ,J-1 a nd .J7 ). Burs or foreign matter iu sear notc h. Failure of bolt lo retract suffici ently. Failme to tire ________ __ _ W eak recoil spring ___ ___ _ Heplace recoil spring (p:1rs. 63 a nti 66 ) . \\' orn or broken !iring Replace fu·ing pin (pa rs. 5-l pin. nnd 57). \Y orn or broken sea1· H.eplace se~u· spring (p:.tr~. -1-1 pring. a nd 47). Defective sear or ha mm e1· Replace sca r (pars. -+-+ mHI -l7 ) or ha mmer (par . 54 w1d 57) . Weak ejection__ ________ _ \'Yarn ejector_ __________ _ R epai r ejecto r (pars . .J -1 and 1 AGO 4471B 47 ). 19 Table II. Malfunction CHAPTER 4 T1·oubleshooting-continued Probable cause Corrective aclion Failure to eject ________ __ JJirLy or clogged ga ports _ Clean and properly adjust cylinder assembly ga (pars. 67 a nd 70). Broken ejector _____ ____ _ Replace ejector (pars. 4<1 and 47). Weak or broken ejector Rep lace ejector lock a nd/ or spring (pars. 44 an d 47 ) . lo k and / or ejector lock pring. Failure to extract ___ ____ _ Damaged or broken ex- Replace extractor (pars. 54 and 57). tractor claw. Broken or missing ex- Rep lace extractor spring (pars. 5-l and 57). tractor pring. Failme to pull off with Sear pring not correctly Reposition ear spring (pru· . 44 and 47). positioned. change lever set at For A. Muzzle depre sed. REPAIR Section I. 32. General General a. Information and instru ctions contained herein are supplem entary to instruction fo r the using organization contained in FM 23- 15. b. In tltis publi cation, the main group of th weapon are d.i sassemblecl, inspected , replaced or repaired , and a ... em bled. For information on elisa sem bly of the weapon permitted by organizational maintenance per·onnel, refer to FM 23- 15. 33. Cleaning and Lubrication a. General. R efer to FM 23- 15 for using arm information on cleaning, cleaning agents, and precautions to be ob erved in cleaning. Inform ation for ordnance personnel is given in b through e below. b. Cleaning JYI ateriel R ece·ived From Storage. (1) Materiel received in or lnance ·hops from storage \'\rill be cleaned by any available applicable cleaning process (TM 9- 1005). (2) If some time is to elap e before t he .tart of repair or rebuild operations apply a light grade of preservative oil to all polished metal surfaces t o prevent ru ting. c. Cleaning Ajte1· Repai1·. After repair operation and prior to assembly remove sh op dirt and other foreign matter from al l m etal surfaces by any avai labl applicable cleaning proces: (TM 9- 1005). d. Cleaning After hop I nspection. After in-proress shop inspections clip parts in a tank containing fingerprint remover oil (type A), remove (use rubber gloves) , and dry thoroughly with dry, ·ompressed air (provided with moi t ure filter trap.) or by wiping \\·ith clean, unt -free , dry cloths. pply preservatives a soon as possible after cleaning. e. Lubrication. Oil and lubricate the rifle in accordan ce wi.th instructions in F f 23- 15. General in t ructions on lubri cation a re covered in TM 9- 2835. Lubri cating materials are listed in ORD 3 NL I - 1 and t heir uses are explained in Tl\II 9- 850. 34. General Repair Methods a. Disas embly and As embly Procedw·es. (1) In disassembung a unit, remove the major subassembues a nd a semblies whenever possible. Subassembli es may then be elisa ·sembled, a necessary, into indi vidual pa rts . (2) Dw·ing a. :cm bly, ·uba ·semblies ·hould be a:sem lled first and then in tallecl to form a complete unit . 20 AGO 4471B AGO 4471B 21 (3) omplete disassembly of a w1it is not always necessary in order to make a required repair or replacement. Good judgment ·bould be exercised to keep el i. assembly operations to a min imum . b. Replacement of Parts. ( I) Un erviceable and unrepairable as. emblie will be broken down into items of issue and serviceable part s wi ll be returned to stock. Parts or a semblie Lhat cannoL be repaired or reclaimed to the .tandards et forth in thi. pub lication will be rep laced as indicated. (2) \\<hen assembling a unit, rep lace taper pins and cotter pin with new one , if possible. If scre\YS or nuts are damaged they should be replaced. (3) All. prings should be replaced if they are broken, kinked , cracked, or fail to f\m ction properly. (4) If a r quired tPW part is not avail able, recondition ing of the old part i. req uired. Such parts should b examined carefully after reconditioning to determine their serviceability. C se of Tools. (1) Care mu t be exercised to use tool that are suitable fo r the task Lo be performed , in order to avoid mutilation of parts and / or damage to tool.·. (2) Special tools (ch . 2) are provided for maintenance of the rifle. These tool· should be used only for the purpo e for \Yhich they are intended. d. W elding and Ri1• Lin g. For v-·elcling instruction and weldi ng material ·, refer to Tl\1 9-2852 and ORD 3 S -L K- 2. e. Repairing Damaged Th rea ds. Damaged thread should be repaired by use of a th read restorer or by chasing on a lathe. f. Fini8hed 8wjaces. Repain al l ·urface on wbjch paint has deteriorated or become damaged (TM 9-285 1) . c. 35. Removal of Excessive Carbon and Rust Light rus and carbon may generally be removed with a cloth moistened with ugh oil or rifle-! ore cleaner olvent cleaning compound. If t his does not suffice crocu. cloth or fine abrasive cloth may be u eel. are should be observed not to scratch or alter surface cleaned and to t horoughly remove all dirt and abrasive before assembling the parts. Avoid t he u c of any abra. ive that may remove phosphate coating, zinc p lating, or cadmium plating. 36. Removal of Burs From Threads, Screwheads, and Working Surfaces screwheads, threads, and like surfaces should be removed 1viih a fine file. B w-s or roughness on working sw{aces ·hould be removed with a fine sharpening stone. Caution: Care shoul I be observed to sLone and file evenly and lightly a nd not to remove more metal than is ab. olutely necessary and to maintain correct contow· of .-urfaces worked on. P art· or a semblie hou ld never be altered in any way that would affect interchangeability of parts. 37. Wooden Components D ents or m ut ilations that do not affect trength or general appearance may be sanded out.. Wood dough (plastic wood ·ub titute) may be u eel, if practi cable. Unvarnished \\·ooden component , such as hand gua rds will be anded all over. Patching is pemitted where strength is not affected. Components cracked in such a manner that strength is affected will be replaced. Unvarnished wooden components .-hould b t reated with fungicide solution G-4 (powdered form) mixed in linseed oi l mixtme. 38. Repair of Damaged Machined and Polished Surfaces Rough sp ots, cores, bur , galling, and gouges will be moothed so that t he part will efficiently perfo rm its normal fLm ction. The finish of th repaired part will apprm.:imate that of Lhe original finish. In performing any of these operations, riti cal dimensions will not be altered. 39. Barrels a. Barrel · \l"ill be free of con·o ·ion, powder fouling , bu lges, and rings. M uz7iles will be hee of bur·. Fine pits are allowed if they do not affect the sbarpnes of lands materially. Pits are allmved in the chamber if they a re nol large enough to cause extraction difficulties. Barrels wi ll be replaced if lands are worn to the extent that accuracy is affected or ir pits are as wide as the lands, grooves, or are more than three-eigh lh.in ch long. b. P owder burns, exterior irregularitie ·. and deformation not affecting t he functimung or appearance are acceptable. 40. Springs Replace a ll spri ngs that are corroded, weak, or 41. Test all man ually operated safety feaLw·cs for satisfactory operation. 42. Function-Firing a. Foll owin g repair, fire each rifle as follow. if facilities are available i11 t hird or fou rth echelon: Rounds AGO 4471 B torLccl. Functioning of Safeties During t he entire life of the weapon, polishing and stoning are necessary to relieve fri ction and to remove bw·s set up by firing. B urs on 22 c[j 20 20 AGO 4471B Gas port Medium Medium C flange le-ver position Full Automatic Reduced uutomut.ic 23 If weapons do not function satisfactorily , additional rounds are authorized. Weapons that fail to meet the test are to be corrected by replacement of defective component or by performjng such repair as required. b. All weapons will be cleaned as soon as possible after all firing tests have been completed and each day thereafter for 3 days making a total of -! consecutive days. An alternate method of scheduling cleaning operations is to clean al l weapons immediately after function-firing and two successive times following the fu·st cleaning; cleaning intervals should be at least 16 hours 1\·ith not more than 72 hours between any two successive cleanings. c. Special care should be taken to insure that bolt faees, pistons, breech end of receiver, and other parts subjected to burned powder residues are thoroughly cleaned. These parts should be scrubbed with a bristle brush moistened with rifle-bore cleaner solvent cleanillg compound . d. A single cleaning of the bore and chamber of function-fu·ed weapons with steam or hot water (not less than 200° F.) is acceptable in Lieu of the cleaning in b above . The steam or hot water may be applied by hand or machine and the bore and chamber air-dried. The bore and chamber will then be scrubbed with a snug-fitting wire brush dipped in rifle-bore cleaner solvent cleanillg ompound. Three m·y patches will then be passed through the bore and chamber, followed by one patch saturated with prescribed oil. 43. Table III. Operation No. 9 10 11 12 13 1-! 15 16 17 18 19 20 21 22 23 24 25 The information in table III illustrates the sequence of operations necessary dming repair of the weapon. Special machines, tools, and gages required for an operation are indicated opposite the operation. Operations Ra ttle Sheet for Cal ..SO Browning Automatic Rifle Operation No. Operation I ?>•lachine I --------- \------------------------------ 1 2 Tools 4 5 6 7 8 26 27 28 29 44. Unpack. D egrease________________________ _ See Tl\1 R ecord seri al numbers. Di assembl e into ubassemb lies ______ ----- - --- 7:266-±50 Disasseml le subasse mblies ______ ____ --- ---- - - 7:266-±50 Clean al l parts. Inspect wooden com ponents. Inspect metal components: Inspect for excessive "·ear in bolt lock shoulder in receiver. Inspect bolt assemb ly. Inspect gas cylinder_ _______ ___ ---- -- ---- ~ 556-~ 1 -±-l5077204 Inspect gas pi ton ___________ __ - -------- ------- - - -- 5077201 I 24 1\ 1o.chi ne Tools Gages Inspect a ll other parts for serviceability. R emove barrel from receiver if Vise ___ _ necessary. Inspect barrel and receiver: Inspect barrel visuall.' · for pits aucl dents. Inspect bore _________________ _ Assemble barrel to receiver or re- Vise____ ba rrel if neces ary. Do necessary repai ring or part. nR req uired. Inspect. Do necessary polishing of pru'tR aR required. Inspect. R epair and sand stoc k and forearms. Inspect. Sandblast parts requiring refin ishing. R efini sh. Inspect. Assemb.le subassemb lies ________________ _____ Assemble subassemblies to ri.fie ______ --------Inspect. Function-fire. Do necessary repairing. 6316006, 6316005 7265788 55643-J-3 6316006, 6316005 7266-±50 7266450 Clean rifle. Final inspection. Record serial uumher. Pre erve and pack. Gages 9- 1005. 3 Operation Note. D o operations 23 anU 2-J again if repair is performed. ~119/B.ri :J I I -----------------------------1- ------- Operations Route Sheet Table III. Operations Route Sheet jo1· Cal .. 30 B1·o wning ilutomatic R·ifie M19181Hi- continued AGO 4471B Section II. TRIGGER GU ARD ASSEMBLY Removal and disassembly Refer to FM 23- 15 for removal and clisas embly of the trigger guard assembly (fig. 6). 45. Inspection a. Geneml. In spect all parts for damage and excessive wear that might cause malfunction , burs, rust foreign matter in recesses, deformation, and free action with mating parts. b. TTi ggeT (Riveted) (figs. 6 and 7). Inspect trigger for full action on pin with respect to guard. In pect com1ector pin to see if it is riveted securely in place. Rear proj ections at the h eel of trigger must be free AGO 4471B 25 SEAR-5564299 L1-!Jib.. COUNTERRECOi SPRING--:-5 153133! \SEAR RELEASE STOP ~IJ.£VER-6147487 ~ EJ ECTOR-60 19639 /;,_ MAGAZINE CATCH SPRING-5153 130 EJECTOR ~TRIGGER CONNECTOR-6019636 LOCK-~ ~ 5022225~ ···~~ EJECTOR LOCK ' / SPRING-5153132 f / > MAGAZINE RELEASE-5022242 " 0 RA PD 134734 Figure 6. Trigger (Jnnrrl rts-Selli.bly- xplorled view. > "0 MAGAZINE CATCH 5022216 TRIGGER CONNECTOR6019636 TRIGGER ASSY6019684 88 DEG SEAR-5564299 SEAR RELEASE STOP LEVER-6147487 CHANGE LEVER5509Q71 EJECTOR-6019639 Figure 7. SEAR CARRIER -6147499 Tmpo1·tant point to be inspected on trigger gum·d assembly pa-rts. RAPD 917550· · of wear that would affect operation of safety. Top rear corner should be sharp, not beveled, at point where it enters the notch in change lever. Inspect heel and tip for sufficient clearance with bore of guard for full retraction. c. Trigger Connector (figs. 6 and 7). Inspect top bearing surface of trigger connector ·where it contacts sear and sear rel ease stop lever. This is a critical surface, as excessive wear or burs may affect function of sear and stop lever. Inspect rear toe of connector where it contacts tongue in change lever apertme and fron t sloping surface (sear carrier ramp) for >Tear and burs. Profile must be clearly defined and all operating and camming surfaces free of excessive wear that may affect functioning. d. Sear (figs. 6 and 7). Inspect sear for looseness orr pin. Inspect sear pin for urrclue wear at ends and for burs. (Vi ear of pin at end is increased clue to movement in elongated hole in t rigger guard.) Inspect sear for deformation, wear, and burs on forward lower camming sm·face contacting connector and on rear upper camming surface contacting sear release. Rear beveled camming smface must be perfectly smooth. Inspect sear notch faces (rear and top) for wear and bm·s. Sear notch should be smooth and free from lm ife or wire edge. No te. Sea r pin holes in trigger guard and t rigger pin holes in sear carrier are elonga ted to allow play of mec hanism, relative to counterrecoil spring, to absorb jar of counterrecoil on t he mechanism. e. Sear Spring (fig. 8). (1) D etermine if sear spring is of latest desig·n. Modify sear springs of ea rly manufacture, which do not have the %'2-inch notch at the rear end, to conform to the latest design (par. 46g). (2) Inspect sear spring for functioning \Tit h sear and connector, looseness in retaining slots in trigger guard body, deformation, fracture, and ''ear. The two side prongs of spring should bear evenly on shoulders on fonYarcl end of sear. Center prong lies below forward end of stop lever and bears on forward ramp of connector. Prongs are even when at rest and curved down\rard. Forward end of spring should be well seated in its lateral notch in trigger guard body. f. Sear R elease Stop L ever (figs. 6 and 7) . Inspect sear release stop lever for \Year and burs on forward lower surface where it contact s conn ector and on rear sm·face where sear release strikes. Rear nose may become expanded clue to action of sear release and thus bind in sear. g. Sear Carrier (R iveted) (figs. G and 7). Inspect sear carrier for loose, fractured , worn, or burred connector stop (riveted on right end) . Inspect connector caroming surface for wear a nd burs. h. Change L ever (figs. G and 7) . Inspect change lever for functioning with connector and trigger, deformation, and free movement in trigger guard body (should be close fit). The change lever moves freely in its various positions, operates as inten ded , and remains in the selected position. 28 i. Change and Stop L ever Spring (Riveted) (fig. 6). Inspect change and stop lever spring for functioning with change lever ( houlcl bear fi1·mly in notches) and sear release stop lever, deformation, and cracks. Inspect stop lever prong for fracture, looseness on rivet, and excessive deformation, causing weak action on stop lever. j. Magazine Catch (figs. G and 7) . Inspect nose of catch for wear and burs (edge should be sharp) . Catch must securely hold a loaded magazine. lc. ~Magazine Catch R elease (fig. 6). Inspect magazine cat ch release for free movement in trigger guard body and catch, deformation, and fractured nose. l. E.iectoT (figs. 6 and 7). Inspect nose of ejector for deformation wear and bms. Upper forward corner of nose should be well defi..11~d. If nose is bent or worn, it fails to eject properly ; if too long, it binds on bolt and causes weak ejection. It must fit the trigger guard body. It must fit the trigger guard with sufficient freedom to permit normal removal without perceptible looseness. m . Ejector Lock (fig. 6) . Inspect ejector lork for free movement in well in trigger guard housing. n . T rigger Guard Body (fig. G) . Inspect tri gger guard body for deformation, for worn and burred spring retaining grooves, and receiver retenLion groove (rear end). Trigger guard body assembles freely to the receiver without apparent looseness or sideplay. o. Counterrecoil, Ejector Lock, and nfagazine Catch Sp1·ings (fig. G). Inspect springs for function and fracture. 46. Repair a. General. Replace all broken, "'01'11, or othenYise unservi ceable parts. R emove bms and rust as explained in paragraphs 35 and 3G. b. W ealc Ejection. Weak ejection of cartridge case is caused by the neck of ejector scraping on bolt, the neck being bent or too short, or the nose being worn. To correct, grind off nose, being careful to maintain angle; straighten or replace ejector. Space between ejector and bolt is not more than on e thirty-second inch. c. Slide Fai ls to Coclc. This condition is clue to damaged sear, broken sear spring, bms, foreign matter in sear notch in slide, or failure of bolt to move far enough to the rear on recoil movement to cock the slide. Examine parts; clean and replace if necessary. d. Stoning Nose of SeaT. If nose of sear or sear notch in slide becomes worn or burred , stone llghtly with a fine-grained sharpening stone. Exercise care to maintain retentive angle and stone to polish only. If too mu ch metal is removed from top face of sear, the face becomes too shallow to retain slide, clue to interference of rear end of sear (release cam extension) with th e slide, t hus hol cllng sear notch out of engagement. Test sear retentive action after stoning, and if found questionable, replace sear. Dress in slide in like manner. AGO 4471B AGO 4471B 29 e. Correcting Trigger Pull. (1) uight t1·igger pull. Light trigger pull is caused by foreign matter or burs in sear notch of slide or nose of ear. Such burs or· foreign matter prevent nose of sear from seating fully in sear notch in slide. To correct, remove fo reign matter or stone burred surfaces as m.rplained in d above. Replace badly burred or damaged parts . A light pull is also due to a weak or broken sear spring that does not seat the sear fully in the notch in slide; correct by replacing sear spring. (2) Excessive trigger pull. Excessive trigger pull is caused by binding on components of trigger group foreign matter in trigger guard body, or bw-s on t rigger, connector, sear pin, or sear; correct by removing foreign matter and stoning bw-red surfaces. 48. Functional Check a. Inspect trigger guard a:. embly for looseness, fw1ctioning, and cofunctioning of its a sem blies and parts. Trigger guard assembly assembles freely to receiver without apparent looseness or sideplay. b. Check function of trigger, cmmector, and sear spring with trigger guard assembly held horizontal, tipped forward, and tipped back. If sear spring is not bearing properly on forward shoulders of sear and center prong on connector, the connector will not ftmction properly when trigger guard assembly is tipped . Check functioning of trigger, ear, and stop lever, when change lever is set at A position (normal cyclic rate), F po.-ition (slow cyclic rate), and S position (safe) (fig. 9). f. Fitting New Trigger Gum·d. In fitting new trigger guard to receiver, it may be found that trigger guard retaining pin holes in trigger guard body and receiver are not concentric. In such event, stone off rear beveled surface of trigger guard or mating lug on receiver slightly to aline holes. Use fine-grained sharpening stone. g. Jl!Iodifying Sea1· Spring . File row1ded notch in sear spring with small rattail (Swiss pattern) file to the dimensions prescribed in figme 8. The notch facilitates removal and redu es breakage of sear spring. RAPD 910448 // 3/64 / RAD\ , II Figure 8. 47. fi'igw·e 9. I Filing notch in senr sp1·ing. Assembly Refer to Fl\11 23- 15 for assembly of the trigger guard assembly (fig. 6). 30 AGO 4471B Various posilio11s of change lever on assembled trigger guard assembly. hange lever set at A (vertical position) (fig. 9). When change lever i set at A position and tl·igger is retracted, the connector rai ·es the for\Ya.rd end of sear and sear release stop lever together and holds them up as long as trigger is held fu lly retracted. Thus the rear end of the sear is depressed and held from engagement with sear notch in slide, while the rear end of sear release stop lever is also depressed, preventing sear release from stri king caroming smface on rear end of sear. When trigger is released, sear and sear release stop lever both return to their normal positions. (2) Change lever set at fi' (fonuaTd position) (fig. 9). When change lever is set at F po ition and trigger partially retracted, the connector raises the fonYard end of sear and sear relea e stop lever together. As trigger is further retracted, the connector, still rising, is caromed from under front of sear by camming surface on sear carrier, and continues to raise forward end of sear release stop lever, and holds it in rai. eel position as long as (1) AGO 4471B 31 trigger is held fully retracted. Therefore, the sear is free to function when acted upon by the sear release, willie the rear end of the ·ear release stop lever is depres ·ed to a point when~ it will not block the action of the sear release upon the carnming sw·face of rear end of sear. Thi s action produces the slow cyclic rate of fire. (3) Change lever set at S (rear position) (fig. 9). When change lever i . et at S po ·ition, the trigger is blocked by t he change lever and prevented from ri sing, lifting t he connecto r and disengaging the scar. 49. Installation HPfer Lo Fl\I 23- 15 for installation of t he trigger guard assembly. Section Ill. 50. BARREL AND RECEIVER GROUP Removal and Disassembly a. RemoL'al of Barrel Fr01n Receiver (fig. 10). ( I ) Only remove the barrel from the receiver when replacement is necessary or for gaging depth of chamber. (2 ) Place barre l in barrel holding vi. e block 6316006 (fig. 4) and elamp in vi ·e. Fit receiver and barrel open end "Tench 6316005 (fig. 4) on receiver, and unscrew (right hand thread) receJver from barreL b. Disassembly of Barrel Assembly (fig. 11). (1) Kever remo\'e components attached to barrel except 11·hen re- placements are nece · ary or for the purpose · of salvaging. (2) Drive off front sight blade, if neces ary to replace. (3) Drive out the front ight key pin , ch·ive the front sight base off to the front and remove the front sight key. (4) Drive out ga cylinder tub bracket pin and d rive gas cy linder tube bracket off to the front . c. Disa. sembly of ReceiveT Group (fig. 12) . !ide the operating handle out of its guides on the receiver. Press in on the operating handle plunger and push out t he op(2) erating handle plunger pin toward the countersunk ide of the plw1ger. Then remove the plunger and spring. Lift the bolt guide sprin g out of its seat in t he bolt guide with (3) the rim of a cartridge. Remove the guid and spring from the rece1ver. (-!) Depress change lever sto.p spring assembly until clear of groove in change lever stop spring retaining pin, hake pin from receiver , rotate ·pring down and push stop from apert m e lJl receiver. (1) 32 AGO 4471B AGO 4471B 33 r - -- ----BARREL ASSY-6508769-------.. FRONT SIGHT BASE-6019630 FRONT SIGHT KEY PIN-5022230 GAS CYL TUBE BRACKET--6019634 GAS CYL TUBE BRACKET PIN-502223 1 RECEIVER GROUP (SEE FIG 16) RA PO 134735 Figu re 11. BaTrel rt. sembly-e."Cplorlerl view. > Cl 0 > Cl 0 *LEFT BOLT SUPPORT6019663 BOLT GUIDE--6147130 * BOLT SUPPORT RIVET- 5022243 ~'TOP /['\ _l PlATE-6019653 . - OPERATING HANDLE PLUNGER PIN-5022236 SUPPORT)~ *BOLT RIVET-5022243\ ,_.a ,: .~ • cHANGE LEVER STOP SPRING), RETAINING PIN-5022228f ~ ~ /~ 7~ *BOLT GUIDE SPRING-5022251 * CHANGE LEVER CHANGE LEVER STOP STOP SPRING SPRING-5022200) ASSY-6019697 }-{CHANGE LEVER STOP-5022207 I (!) OPERATING HANDLE PLUNGER-5022241 *PART OF RECEIVER ASSY-6535472 RA PO 134736 Figttre 12 . R eceiver gro up-exploded view. (5) Buffer tube is threaded into receiver and is never removed except for replacement or repair. To remove, clamp receiver in vise with leath er jaws, first inserting buffer tube alinement tool· spacer 7113328 (fig. 4) inside faces of receiver walls to prevent sp ringing of the receiver, and then unscrew buffer tube with strap wrench (fig. 13) . - - - STRAP WRENCH BUFFER TUBE All NEMENT TOOL SPACER-7113328 RA PD 91399C Fig ure 18 . Removing btt:ffer tube. (6) If necessary, remove top plate of receiver by driving out of grooves to front of receiver, using a block of hardwood as shown in figure 14. 51. Inspection a. Ban·el. (1) General inspection. Inspec barrel for deformation, alinement in receiver, crossed threads, rust, corrosion, wear , burs, and foreign matter in gas port and extractor aperture. Barrel must aline exactly with receiver 'vhen assembled, in order that rear end of gas cylinder tube will fit mating slot in receiver; front sight will aline properly; and extractor aperture will be correctly positioned, drilled, and pinned during manufacture of the rifle after barrel is assembled to receiver. A draw mark is then placed in barrel and receiver for proper alinement upon assembly. If draw marks do not qualify, fashion a shim from shim metal. 36 AGO 4471B I AGO 4471B 37 If barrel and buffer tube are removed , inspect for crossed threads. (3) (-±) Inspect bolt lock recess in top of receiver for wavy. (2) Inspection .foT sen iceability. (a) General. In pect the barrel (fig. 11) as a whole from th~ tandpoint of servi ceabili ty. Before in pecting the barrel, all metal and other fouling must be removed a nd the barrel " -i peel dry. Accuracy of fire is the main point to con:ider when inspecting a barrel. Accuracy is reduced in varying degrees by bulge , ero ·ion, and pits in the bore. The extent to which these defects " ·ill reduce accuracy is determined by two methods; namely, vi ual in spection and bore gaging. (b) l 'i ual inspection. For visuaJ inspection, using barrel reflector 7265788 (fig. -1), hold t he barrel so that its interior is illuminated and examine the bore. If the barrel is not bent or other"-i ·e deformed, if t he bore appears free from bulge and large pit , a nd if the land are sharp and uniformly distinct, it is ervi ceable providing it i in good condition othenvi e. A bulge i. indicated by a h adowy depres ion or a ring in the bore. It may often be detected al o by a bulge or raised ring on t he e:-.'terior surface. If the barrel is pitted to the extent that the sha rpness of t he lands i affected or if it has a pit or pits in the lands or grooves large enough to perm it pa age of ga a round t he bullet (that is, a pit the width of a land or groove and thr ee-eighth inch lon g or longer) t he barrel will be scrapped. (c) Bore gaging . Barrel inspected and found erviceable by visual test will be bore-gaged, u ing breech bore gage 5564343 (fig. 3) . Barrel will be replaced if gage reading exceeds 0.310 in ch in hands of troops in field or 0 .306 inch at preembarkation inspection. b. Gas Cylinder T ube Bmclcet (fig. 11). Inspect ga cylinder t ube bracket for looseness on barrel, missing or loose pin, alinement of gas port with barrel port, and for worn or burred dovetailed mating grooves. (Bracket is a drive-fit on barrel and gas port is drilled t hrough bracket and barrel after assembly at manufactme.) c. Fmnt Sight (}roup (fig. 11 ). Inspect front sight base for looseness on barrel ; mi ing, loose, or bun·ed key; and worn keyway (on barrel). Inspect for mi sing front sight key pin, looseness of pin in ba e, and for looseness with key . Inspect front sight blade for position (stakes) , looseness in base mating dovetail, worn or burred dovetail (mal and female), deformation, and shine. cl. Receiver (fig. 12). (1) Inspect receiver for excessive wear, deformation (pinched sides due to squeezing in vise), burs, rust, and foreign matter in recesses. (2) In pee for loose rivets in bolt supports and for cracks in barrel end and bridge. l must contain eight ]Jlines. . . h ld (7) Inspect receiver for recess cut (fig. 15) · Th~ · recess cut s. ou . t be ch·illed by depot maintenan e on all recmver. not hav111g I in accordance with dra\\ing D 6i:i3i:i373. ' -FiguTe 15. WITH RECESS I . Compm·ison of -receiver with and without recess cut. e. Operating Handle Group (fig. ~2). ~1spect operating handle. for functioning a nd free movement in 1ts slideway . Inspect plun~er for functioning and free movement in well. Inspect plunger spnng for . functioning and fractm e. f. Bolt Guide Group (fig. 12) . Inspect bolt guide for s~sta.med f~nc~ tioning with bolt, looseness with pring looseness of pnng m rece1ver I apertme and weak spring action. g Ch~nge L ever Stop Group (fig. 12) . Inspect change l~ver ~top for fun~tioning with spring, wear, and bms, loosenes~ on sp1.'mg (nveted) , and weak spring. Inspect spring for looseness m recmver aperture. Inspect pin for looseness. . . . . .· h. Gas Cylinder Tube Retaining Pin. ~1 spect re~lill1lg p1~ for spr.mg retention with depression in receiver, locking functwn of ~ey ~ unde1cut · · (left s1"de) Inspect spring for looseness on pm (nveted), dem rece1ver · · · · f ·r . formation, or fracture. If spring becomes loose from pm , pm o ear 1e1 39 AGO 4471B Ar!() dd'71R ~urface , wear and burs especia lly where lock seats when bolt J.s locked . Insp~ct surface by refl ecting lig.h ~ on it from a small ml rror or a bright too1. This surfa e i cnt1cal a nd afie?ts headspace. (5) Inspect top plate for looseness ( hould be dtwe-fit) · (6) Inspect buffer t ube for t ightnes. on receiver. It sho~ld be free of dents t hat would cause buffer cones and cups t o freeze and manufactme cannot be rotated to be withdrawn from receiver; however, pin 5022232 of latest manufactme has a screwdriver slot on end for removal of pin when spring breaks. 52. Repair 53. Assembly and Installation a. A embly of Receiver Group (fig. 12). (1) Install top plate, being careful no to deform the dovetail. (2) Install buffer tube on receiver as sho\\'·n in figure 20, being sure that one of the eight groove in the head of the tube li e centrally horizontal with the top of the receiver with nose down. 'lamp receiver in vise, first inserting the pacer 7113328 (fig. 4) of the buffer tube alinement tool 6316001 between inside faces or receiver walls to prevent queezing of receiver, and insert parallel 7113327 (fig. 4) of buffer tube alinement tool into receiver, \Yith keyed end toward buffer tube end of receiver a. shown in figure 16. 'tart the buffer tube into the ends of the receiver and inser plug 7113326 (fig. -±) of buffer tube alin ement tool as shom1 in figure 16. Tighten buffer tube with :trap \Yrench until plug engages keyed end of parallel. a. General. Replace all broken, worn, or otherwise unserviceabl e parts. Remove burs and r ust as explained in paragraphs 35 and 36. b. R eplacing Unserviceable Barrel. (1) Disassemble barrel from receiver (par. 50). (2) Assemble new barrel assembly, which includes front sight base and gas cylinder tube bracket. Screw up barrel until draw marks on barrel and receiver register. Assemble gas cylinder tube to bracket; then check fit and alinement of rea r tang and retaining pin holes in tang and receiver. If tang of tube does not mate without binding, turn barrel until this is accompli bed. Barrel ·hould draw up tightly to receiver so there is no possibility of vibrating loose. If there is no draw mark on barrel, draw up until tube alines as above and check position of extractor cut by assembling bolt with extractor assembled. (3) If barrel does not draw up to proper position, ch·ess rear face of shoulder in a lathe. (4) Never alter the receiver to obtain draw-fit. When barrel is alined, check alinement of gas cylinder tube, front sight, and extractor cut. If barrel requires much shimming or dressing to aline, headspace may be affected. c. Front Sight Blade Out of Alinement. This is usually due to enlarged dovetailed aperture in base. Peen lightly along upper edges aline sight blade (by eye), and stake, using old stake mark. Base pin may be missing; if so, replace and aline blade. d. Rough or Wavy Swface of Bolt Locking Recess in R eceiver. If surface of bolt locking rece s in receiver is bmred or wavy, correct by removing · top plate (par. 50c(6)) and -toning rough or wavy surface smooth with a fu1e-grained sharpening stone Exercise care to stone evenly and remove as little metal as possible, as this surface affects headspace. Check headspace (par. 27) after stoning. e. Loose Spring on Gas Cyl-inder Tube Retaining Pin. If spring becomes loose hom body of pin, it may be impossible to withdraw pin by ordinary methods for replacement. In such event, attempt to revolve and shake pin out of aperture or pull out with needle-nosed pliers. f. Dents in Bu.tfer Tube. Shallow dents in buffer tube are often removed by reaming with an expansion reamer et to the original inside diameter of tube. Larger dents may be swaged out, first by using rod the size of inside diameter of tube and then reaming. If dents are deep enough to cause possible weakening of wall of tube due to this procedure, replace the tube. Test components in tube after repair for free movement. c. Installing Barrel Into Receiver (fig. 10). When installing the barrel, always be certain that it is tight enough in the receiver never to work loose. Screw the barrel into the receiver until he draw line matches that of the receiver. Then assemble the gas cylinder tube to determine whether the gas cylinder tube bracket on t he banel alines properly with the receiver, so gas cylinder tube rear tang slides easily into its aperture in receiver. If it does not, turn the barrel slightly until the alinement is correct. "'hen assembled, check extractor cut in rear face of barrel for position. For assembling new barrel, refer to paragraph 52. 40 AGO 4471B AGO 4471B Note . BufJer tube mu t be at tightest possible position at which the plug and pamllel 1\i.ll engage, u ing shim or h.ims, if ne es ary. (3) In tall change lever stop pril1g assembly in re eiver and ecure with change lever stop pring retaining pin. (4) Insert the longer turned-over end of bolt guide pring in its hole inside the receiver. Then install the bolt guide and hold it while the spring is pushed over lmtil the horter t urned-over end engages the groove in bolt guide. (5) In tall operating handle plunger spring (0.263-in. 0 D, 5 coil ) in the operating handle. Insert operating handle plunger and ecure with operating hanclle plunger pin. Be sme pin is installed with ridge in colmter unk si de of plunger. (6) Inser operating handle group in Licleway on receiver. b. Assembly of Barrel Assembly (fig. 11). (1) Install gas cylinder tube bracket, being sure to aline gas port holes. Secure bracket in place \\ith gas cylinder tube bracket pin (0.1257 x 0.855). (2) Po ition front sight key in groove on barrel and install front ight base. Secure them in place " ·ith the fron ight key pin (0.0907 X 0.505) . (3) Install front sight blade and realine ights. 41 ::Wf'•\..tt<- 71133281 I BUFFER TUBE 11 33 27 ~- AUNEMENT 113326 ITOOL-6316001 > G"l 0 RA PO 9 738C Figute 16. > G"l 0 As ·emlilino bu.fJrr tube lo receil'er. HAMMER-60 19643 .... .... _, t;; BOLT LOCK PIN- 5022226 !BOLT, ASSY)601 9695 FIRING PIN-6019652 EXTRACTOR-5509090 RA PD 134737 Figure 17 . Boll gronp-ex ploded m:ew. Section IV. BOLT GROUP 54. Removal and Disassembly Refer to FNI 23-15 for rcmo\'al and disa cmb ly of the bolt group (fi g. 17). 55. Inspection a. General. Inspect parts for damage, excessive \Year which might cause malfunction, burs, ru t, fo reign matter in recesses, deformation, and free action with mating parts . Figure ] shows im portant points to be inspected. {SIDE YIEWJ BOLT -5509068 (END YIEWl c. Bolt Lock (fig. 18). I nspect rear top shoulder where lock contacts receiver locking aperture for wear and burs. This is an important surface, as it affects headspace (par. 27). Inspect lower rear cam surface where lock rides up on bolt supports and firing pin camming surface for wear and burs. d. ExtracloT (fig. 18). Insp ect extractor spring for fracture, weak action, and looseness in extractor body. Claw nose and retaining shoulder are square, not beveled . e. Firing Pin (fig. 18). Firing pin should slide freely in well and protrusion of nose from forward face of bolt should be approximately three thirty-seconds inch. If firing pin protrudes too far, it will result in punctmed primers. Inspect firing pin nose for pits. Nose must be smooth and round. The camming surface contacted by the bolt lock and rear surface contacted by the hammer must be free of wear that would affect action of firing pin. f. Bolt Link and Bolt Link Pin (fig. 18). Inspect link for excessive looseness with bolt lock and hammer . When assembled, the link bears on rear camming face of bolt lock. g. Hammer and HammeT Pin (fig. 18). Inspect hammer for excessive looseness with link and slide. Inspect center rib of hammer \vhich strikes head of firing pin for wear and bms. Hammer pin must fit snugly in the hammer and bolt link. 56. FIRING PIN-6019652 EXTRACTOR-5509090 Repair a. General. R eplace all broken, worn, or othenvise unserviceable parts. Remove burs and rust as explained in paragraphs 35 and 36. b. Bolt Assembly. If it is necessary to replace one of the parts of the bolt assembly, drive out the bolt lock pin, using a suitable drift. This is a headed pin riveted on one side when assembled . After replacing the unserviceable par t , install a new pin and rivet in plaoe. 'I 57. Assembly and Installation R efer to FM 23-15 for assembly and installation of bolt group (fig. 17). 58. BOLT LOCK-5509072 HAMMER6019643 RA PD 917568 Ji'iguTe 18. Inspection points on bolt group pa.Tls. b. Bolt (fig . 17). Inspect bolt for excessive sideplay and looseness with bolt lock and bolt lock pin (riveted). Inspect firing pin hole for enlargement, and inspect face for corrosion and recessive wear. Firing pin holes a re gaged by fifth echelon organizations. Inspect lower smfaces contacting bolt supports and center feed rib for wear and burs. AGO 4471B Functional Check Check free movement of bolt, bolt lock, link, and hamm er attached t o slide and piston, but with rer.oil spring disassembled. a. RearwaTd Movement. When bolt is locked, the hammer pin should be approximately 0.1 9 inch in advance of the linlc pin and the center rib of hammer slightly in the rear of head of firing pin. When slide is ret racted, it impa rts no motion to t he bolt until it has t raveled back 0.19 inch from extreme forward position. At this point, the ha mmer pin should be directly under t he bolt linlc pin. From t his point, the bolt and bolt lock start to move, and by the t ime the slide bas t raveled 1.20 inches, the bolt shou ld be drawn completely dmvn out of th e locking re- cess and away from locking shoulder of the receiver. AB bolt lock revolves down from locked position, it shou ld cam the firing pin from the face of the bolt. Slide should continue back until it strikes buffer and then rebound 0.10 inch before engaging sear notch. b. Forward M overnent. On forward movem ent, when slide is about 2 inches from its forvvard position, bolt lock should begin to r ide over rear shoulders of bolt supports which cam up its rear end. The bolt link pin passes over dead center, v>ith respect to bolt lock pin and hammer pin, and the bolt lock is forced up by link into locking recess in receiver and t hus levers bolt home; the hammer pin passes dead center under bolt link pin. At this point, t he firing pin should be released from its slot in the tmder side of bolt lock and in a position to be struck by the hammer; the hamm er moves forward 0.10 inch a nd strikes firing pin head and then should move forward another one-sixteenth inch, driving the firing pin to its fully forward posit ion. Section V. 59. ...."'.... ....... .... ;;; ;;I o >- "'"' 1.!1"' -z ...< :l: tj "" 11'1 "' . r-.. M 0 ....w01 ~ <Co::3 _JQ..w O..V'lo:: l:::~u uV'l => ol:u w ~ 0 ur-.. z Q'f _Jr-.. I M wt-0 <( ~~"~ ~J co "'"' 0 1-t-. J _J- <( '() W"<t _J <(M <I) o..O If) l:::z I= 1 02 =>z =>a.. <OV'l roo.. 0 z~ ~~ ~ \~ ~~-~ 11'1 ..., M r-.. wI 1- :5 0.. 1!::::> <I) w 1- 5~ o..O M I=~ ::::>11'1 rol ..., "'r-.. "'..., 0 0.. <( 0:: 03 z~ ou _JV'l J BUTT STOCK, BUFFER, AND ACTUATOR GROUP Removal and Disassembly R efer to FM 23-15 for rem oval and disassembly of butt stock, buffer, and actuator group (figs. 19 and 20) . 60. Inspection a. General. Inspect parts for damage, excessive wear that might cause malfunction, burs , rust, foreign m atter in recesses, deformation, stripped threads on screws and in screw holes, and free action with m ating parts. b. Butt Stock (fig. 19 or 20). Inspect butt stocks for cracks, scoring, and smfaces protruding beyond m etal. Inspect butt stocks for stripped threads in the butt plate and swivel scr ew holes. c. Hinged B u tt Plate fl ssernbly (fig. 19 or 20). Inspect hinged butt plate assembly for deform ation and free action. The hinged butt plate must work freely when it is rotated and mu st be securely held in its open position by the bearing ball in the i1mer butt plate. d. Bu:fJer and Sear R elease Group. (1) Inspect reciprocation of buffer h ead and buffer spring and for free movement in buffer tube. Inspect tube for posit ion and looseness in receiver and worn or burred head keyways. Buffer tube and receiver are qualified at assembly so that keyways aline properly with receiver. One of the eight k eyways in forward end of buffer tube should be vertically alin cl with centerline of bore and receiver so as to posit ion sear r elease vertically, with nose clown, "·hen buffer head is assembled and limit the horizontal for"-ard movement of scar release. (2) Inspect buffer head and fom friction cups a nd cones (fig. 21 ) for free action in tube. L1spect cones for expansion seating in 46 AGO 4471B .I. N ~ r~i N ("') . '() '() N r-.. J 0 I ...J <( > 0 w > 3 V'l I=::::> <I) AGO 4471B I=::::> <I) 47 HINGED BUTT PLATE ( ASSY-6147787 ( BUTT PLATE LOCK SPRING SETSCREVV--5013475 e BUTT PLATE LOCK SPRING---50 137 4 7 BUTT PLATE HINGE PIN--5013746 )/ JBEARING aa......i----(1 BALL--1 04918 OUTER BUTT PLATE BODY--6147321 r--_ ~ BUTT SVVIVEL( BRACKET--731 0000( BUTT SWIVEL ASSY--7310001.JSHOWN J ' or BUTT SWIYEL--7312240 INNER BUTT PLATE--5613688 LONG BUTT PLATE SCREW--5153084 > C) RA PD 134761 0 Figure 20. B tttt stock gro'up-exploded view (early mamtfactttre). > C) 0 .........., ... t:ll BUFFER SPRING---5153131 BUFFER FRICTION CONE--5022217 BUFFER KEY--5 152881 SEAR RELEASE-6147491 \ 1 STOCK RETAINING SLEEVE--5564298 LOCK WASHER--106500 [;';: I Jl INCHES RA PD 134740 Figure 21. B uffer and actuator group-exploded view. ·- mating cups (cones should not seat fully in cups when at rest) and for cracks. Cup and cones must be free of any burs or wear that '\\-ould cau e them to freeze together. (3) Inspect protrusion of buffer head from face of tube. Thi. dimension should be approximately on -eighth inch . Inspect bufier spring for fLmctioning, fracture and ·et. (-±) Inspect sear release (fig. 21) for free movement in buffer head ( houlcl be flu h with forward face of buffer head when retracted) and for binding in notch. Inspect camming face of no. e for wear and burs. Lower fonmrd edge of nose should be slightly beveled and perfectly smooth. e. AcluaioT Group (fig. 21). Inspect actuator and sear relea e for cofunction under spring action. In pect actuator tube for loosene in buffer cap (cap brazed to tube). Tube should be smooth and polished inside. Inspect free movement of actuator in actuator tube (should slide freely). Assemble actuator with blunt end fonmrcl. Inspect actuator spring for functioning, fra ture, and set. f. Stock Retm'rz£ng Sleeve Grou7J (fig. 21). In pect tock retaining sleeve for clearance \\ith actuator tube ancl loo. eness of stop in sleeve and collar on leeve. Stop and collar are both brazed on sleeve. Stock r taining slee e screws on actuator t ube by means of mating threads on stop and in t ube. Hole in stop is air com pre ·sion relief vent. In pect stock retaining sleeve lock wa ·her for locking funcliou and erack:s. 61. WELD HERE Repair a. Gen eral. Rep lace all broken \\·orn, or otherll'i ·e unservi eeable parts. Remove burs and ru t a · explained in paragraphs 35 and 3G. b. Butt lock. (1) tripped threads are often encountered in the screw hole located in the heel of the butt stock using inner butt plate of early manufactme (fig. 20) due to freq uent removal of the butt plate assembly. If the butt stock i · found unserviceable, clue to the above mentioned thread. being stripped, the stock may be utilized by eliminating t he requirement of a screw. This is accomplished in the manner described in (a) through (c) below : (a) 'lachine a tee! pin to the climension · shown in figure 22. (b) Tack-\\·eld pin to lug in butt plate as shown in figw-e 22. (c) Finish off, if necessary, with a fine file. (2) To reduce stripping of threads, remove the large screw from the inner butt plate assembly before removing small screw in heel of the butt stock. Install the small crew first when assembli ng. (3) ·se beli coi l screw thread inserts to repair stripped threads in the butt plate screw holes and/ or the swivel screw hole on butt stocks. 50 1 + 0.010 I ~ L.J NOTE: 0 .16 0 _ _l 0 .005 f 3/8 t ALL DIMENS IONS SHOWN ARE IN INCHES RA PD 91750 Figw·e 22. .Modification of inner bull plate of em·ly nwnufacture. AGO 4471B AGO 4471B 51 c. Aduator Tube. (1) Shallow dents in actuator tube are often removed by reaming wi th an expansion reamer set to original insicl diameter of tube. If dents cannot be removed with an expansion reamer, t ube will be rejected. Test components in tube for free movement after repairing. (2) Remove rust and cl an foreign matter from in side of actuator ube in accordance with instructions in paragraph 35. d. Frozen Btt.f}"er. If buffer head becomes frozen in buffer t ube clue to broken cups, reuwve operating group, trigger mechanism , butt stock , actuator tube with cap, and buffer spring. Soak jammed parts with drycleaning solvent, mineral-spirits paint t hinner , or special preservative lubri cating oil and drive out from front of buffer, using a hardwood plug. If parts do not dislodge easily, remove buffer tube from receiver (par. 50c(5)) , place on hardwood block, and drive out parts as above. If cups and cones are frozen together, soak in dry-cleaning solvent or mineralspirits paint thinner and tap edge of cup until loose. Clean parts thoroughly, test, oil, and install. 62. Assembly and Installation R efer oF I[ 23- 15 for assembly and installation of butt stock, buffer, and actuator group (figs. 19 and 20). 0 0.. < ct: - I 11'1 M Section VI. SLIDE AND PISTON GROUP M 63. Removal and Disassembly a. Removal FTOm Rifle. Refer to Fl'vi 23- 15 for removal of slide and piston group (fig. 23 or 24). b. Disassembly of Slide Assembly. (l ) Remove pin securing piston to slide (fig. 23 or 2-:1-) and unscrew piston. (2) On rifles of early manufactme where a plug i . crewed in to the head of the piston remove the plug. 64. ~ VI 0.. 1.!) z Ci'. 0.. "' - ...< Q :J VI Inspection a. General. Inspect free action of piston and slide with respect to gas cylinder tube and receiver. Piston and slide should slide freely in gas cylinder tube and receiver when rifle is tilted with recoil spring disassembled. Inspect piston retaining pin for loosenes · in slide and wear in piston and slide. A loose fit is provided between piston and slide, when assembled, to insure proper alinement and free movement of slide in receiver. Total end-play of piston in any direction hould be approximately one-eighth inch. b. Slide (fig. 23 or 2-±) . Inspect slide for deformation of ides by pinching or springing, wllicb may cause binding with operating mechanism or receiver, badly dented rear end (indicating frozen buffer), and worn hammer pin hole. 52 AGO 4471B AGO 4471B 53 c. Piston (1) reneml. Inspect piston (fig. 23 or 2-1:) for deformation, wear, and bms on head of pi ton and on gas check bearing ring . Inspect body for mi . ing or fractmed bu hing. Bu hing i ·held by ligbL driv -fit against forward boulder of counlerborc in pi ton body and is not to be removed. If damaged r place piston. In pect pi ton for carbon or ru t. N '<t "'<t <") 1.9" z~ -o- 0 o..o Vl-o < oc Note. On rifles of early manufacture where a plug is screwed into the piston (fig. 24), inspect plug for looseness in head and for rust.; where plug lies below face of piston, inspect for carbo n in recess. 0.. IX- ........- OLU ...JJ u9 UJ::::> .::.:\.9 _...;_ E '-' ~ ~ "'._ ~ "' ~ s "' ·~ ""c 00 N "".., :>. ., <") Ll1 Ll1 ;:::; !'> ------- ~. .J 0 t- U1 ... L j za: s, .§ 0.. a. ..."' U1 Q R. 6 u UJ ::::i lit oc ... Cl ! z ... 0 lit ;:;: (2) Gaging. Gage piston head with 0.-1:94-in ch piston diameter NO GO ring gage 5077201 (fig. 25). Piston bead should not enter gage. To gage, fir t clean piston thoroughly of all carbon and fouling and determine that surfacE's of head ring are mooth and pohshed. \ripe pi. ton head and gage \Vith a slightly oiled cloth and try to pa . gag O\ er piston head. If pi. ton enter gage, it is un erviceable. Pi ton mu t not be oval in . hape, and there musL be no sign s of light bet\Yeen gage and piston head \\·h en held to the light. (Only light pre . ure should be exerted on gage.) ] ~ ., ~ \ CAL. .30 PISTON DIAM t NO GO RING GAGE-5077201 ~ ~ ...,. ~~ ~ .S: "" lit < Cl [7313467 GAS PISTON 1 o r . 5564081 RA Figure ?5. PD 91400A Gaging piston head. d. Recoil Spring and Guid . In pect recoil ·pring for func·tioning, fracture, kink and · t. In pect pring guide for deformat ion loo e bead (riveted), fit, and retention in retaining shoulder: in rcrci,·er. 54 AGO 4471B AGO 4471B 55 65. Repair a. General. Replace all broken, bad ly worn , or otherwise un ervicea ble parts. Remove rust, carbon , and burs as explained in paragraphs 35 and 36. Remove carbon from piston rings with drift of gas cylinder cleaning tool 7268211 (fig. 3) . b. Ali nement of Piston and S li de. The piston and slide are assembled to a loose fit at manufacture. The pi ton is scre1Yed in to lide a nd backed off sufficiently to allow some play in union ; slide and piston are then tested for free sliding fit in receiver and gas cy linder tube. If satisfactory, pinhole is drilled and pin inserted . Pinhole is enlarged to give the Ys-inch play described (par. 6-!a) . 0 0.. <( oc ,.... (") The s]jde is not furni shed as a spare pa rt; th erefore, if the slide is found to be unservicea ble, replace t he entire assembly consi ting of the slide a nd pisto n. lf the piston is still serviceable, remove and alvage for f w·ther use. ole. 0 v -<> lf) I>- c. Frozen P iston . Vinen piston becomes locked or frozen" in gas cylinder, submerge barrel in dry-cleaning solvent or mineral-spirits p ain t thinner until gas cylinder is covered and soak for 1 hour. If this docs not loosen pi ton, place btttt stock on solid surface. and , with wooden block, tap lightly on opera ting handle. Often, considerable force is required to loosen piston. Clean rust and corrosion from piston, gas cylinder, and tube; po1ish and oil. R emove all dry-cleaning solvent or mineral-spirits paint thinner with a clean cloth. d. Def ormed Side Rails of Slide. Side mil of slide may become bent in or out, causing bincling with operating mechani sm or receiver. Rails can be spread or sprung in by using wooden ·wedges, clamping in vise with copper jaws, or ''ith the hands. T est lide after repair for free sliding movement by t ilting rifle. e. Undersized Piston . l ndersized pistons are salvaged by fifth echelon organizations by chrome plating. 66. VI VI <( ..,. ~ N N N 0 lf) ..J UJ :::: lf) J 0 N UJ lf) lf) u V\ J oc ..,. '-0 c:: <( ~ VI 1- z 0 c:: u.. u.. 0 UJ 1- 0 .~ c:: u. c:: Assembly and Installation a. A ssembly of S li de A ssembly . (1) Insert gas piston plug (fig. 24) in piston on rifl es of early ma nufactw-e. (2) Insert gas piston retaining pin (0.1257 x 0.7-! straight pin) (fig. 24) for early manufacture or spring pin (Ys x 1:.{6) (fig. 33) for present ma nufact ure. b. Installati on on R ifle. Refer to FM 23- 15 for installat ion of slide and piston group (fig. 23 or 2-!). Section VII. 67. GAS CYLINDER AND FOREARM GROUP Removal and Disassembly a. R emoval of Gas Cylinder Group. R efer to FM 23- 15 for removal of gas cylinder group. b. Disassembly of Gas Cylinder Grou p (fig. 26). (1) Slide forearm shield to rear and remove. 56 AGO 447 1B AGO 44 71B 57 (2) Unscrew the short and long forearm screws, and remove the screws, the forearm screw washer, and the forearm from the gas cylinder t ube. The long forearm screw is staked to the escutcheon. Never remove the forearm escutcheon except for repair; to remove, insert the screw and pull out. (3) If replacement is necessary, remove the bracket swivel screw and bracket swivel. Spring the front swivel bracket off over the gas cylinder tube. (4) Observe regulator setting to determine position of gas cylinder regulator. Unscrew gas cylinder assembly, remove gas cylinder key and, with combination tool 7266450 (fig. 4), remove gas cylinder body. 68. Inspection a. Gas Cylinder Tube (fig. 26). Inspect gas pad for alinement with port in rifle barrel bracket and for carbon . If barrel is not alined properly with receiver or if tube is deformed, the tang will not slide into aperture freely. Inspect interior and exterior of tube for · dents and rust. Tube should be smooth and polished on inside. Inspect the six gas escape ports for foreign matter. b. Gas Cylinder Assemblies. (1) Inspect gas ports for carbon and foreign matter and cylinder for crossed t lu-eads wear, and burs. Inspect gas pressw-e relief vent in gas cylinder regulator (fig. 26) for carbon ancr foreign matter. (2) Clean the gas cylinder assembly as prescribed in (a) through (e) below. (a) Insert the large recess cutter of the gas cylinder cleanin g tool 7268211 (fig. 3) into the la rge recess of the gas cylinder body (A, fig. 27) and rotate the tool. (b) Insert the long recess cutter of the tool 7268211 into t he regulator recess of the gas cylinder body (B, fig . 27) and rotate the tool. Caution: Always insert the tool through t he large unthreaded opening to avoid damage to the threads in the body. (c) Insert the short recess cutter of the tool 7268211 into the recess of the gas cylinder regulator assembly (C, fig. 27) and rotate the tool. (d) Insert the drift of the tool 7268211 into the gas ports of the gas cylinder regulator assembly (D, fig . 27) and rotate the tool. (e) Clean all parts with a cloth saturated with rifle-bore cleaner solvent cleaning compOlmd. Inspect ports fo r cleanliness. Dry parts but do not oil the inside of the body or the outside of the regulator assembly. 58 AGO 4471B GAS CYLINDER REGULATOR ASSY-7267816 RA PD 253234 Figure 27. AGO 4471B Cleaning the gas cylinder assembly. 59 (3) Inspect gas cylinder body for wear, using 0.503-inch gas cylinder p lug gage 507720-± (fig. 28). This is a 0 GO gage and should not enter the gas cylinder body. Wipe cylinder body and gage with a slightly oiled cloth a nd try to insert the gage into the cy linder body (fig. 28) . If the gage enters cylinder body, it is un servi ceable and is to be replaced. (Only light pressure should be exerted on gage.) CAL .. 30 GAS CYLINDE R NO GO PLUG GAGE-5077204 /. RA PD 90922C Figu1'e 28. Gaging gas cylinder body. (+) Inspect the gas cylinder regulator (fig. 26) for ea e in installing in body, clogged port holes carbon depo it, bms or wear ; illspect t he body key for di stortions that would affect functioning and for burs or wear; in.spect body pin for serviceability. c. Forearm Group (fig. 26). Inspect wooden forearm for loose escutcheon, scoring, and racks. Inspect shield grooves for cracks and inspect shield for deformat ion. Inspect escutcheon for worn threads. d. Front Swivel Bracket (fig. 26). L1spect front swivel bracket for looseness on gas cylinder tube. It should be positioned fu·m ly just ahead of forearm . 69. Repair Note. The gas cylinder tube bracket pin hole is drilled at manufacture after the barrel is a]jned to receiver with respect to extractor cut, to insure aEnement of gas cylinder t ube bracket and tube with receiver, together with extractor cut and front sight base. This fact should be taken into consideration when assembling new parts. c. Frozen Gas Cylinder Body . If gas cylinder body is frozen in gas cylinder tube, remove tube from rifle, clamp in -.;rise with copper jaw, and 1.mscrew gas cylinder body with combination tool 7266450 (fig. 4). d. R emoving Rust From Gas Cylinde1· T ube. R emove rust, if light, with rifle-bore cleaner solvent cleaning compound and a clean cloth or with a fine abra ive or crocus cloth. Wipe surface with a slightly oiled cloth after rust is removed . To clean gas cylinder tube, use rifle cleaning rod and patches. Clean sam e as rifle bore. If necessary, use crocus cloth. e. Dents in Gas Cylinder T ube. D ents may be removed from gas cylinder tube in th e sam e manner as described in paragraph 61c for rem oving dents from actuator t ube. Correct edges of retaining slots in receiver for tang of gas cylinder tube, if damaged, and replace damaged retaining pin assembly. f. Fittin g New Ga.s Cylinder Tube to R eceiver. In fitting new gas cylinder tube t o receiver , it may be found that pinholes in tang of tube and receiver are not concentric. In such event, stone rear tang on gas cylinder tube t o fit, u sing fine-grained sharpening stone. Make certain t ube is properly alin ecl before attempting to fit (b a boYe). g. Cmcked Forearm . R eplace the forearm if cracked sufficiently to "·eaken or if it indicates t hat t he crack may spread. Oftentimes, a starting crack is checked by drilling a small hole just ahead of it. If slide grooyes in forearm shmY superficial cracks, the section m ay, if not too great, be dressed out and smoothed with a sharp blade. If cracks are in areas where strength of forearm "ill not be affected, repair as prescr ibed in (1) through (5) belo"·· (1) P lace forearm in a vise or under pres ure so that the cracks are drawn together. (2) Drm holes, using a No. 55 drill (0.052 in.) for the reinforcing scre"~s (B021- 7190954). (3) Install reinforcing screws by gripping in t he chnck of a hand drm. (+) Cut off screw and file flush so that no rough edges protrude. (5) Inspect for general appearance. Determine that strength of forearm bas not been affected. a. Gene:ral. Replace all broken, worn, or otherffise unserviceable parts. R emove burs and rust as explained in paragraphs 35 and 36. b. Gas Cylinder T ube Out-of-Line W ith Receiver. If gas cylinder tube is out-of-line with receiver, it may be caused by one of severa l factors: a deformed tube, a missing gas cylinder tube bracket retaining pin, or the barrel being improperly assembled to rece iver. To correct, straighten the tube, replace pin, and / or reposit ion barrel ,.,·ith receiver (par. 52b). T est functioning of slide and piston \lit h tube after repairs. h. Dried-Out Wood of Forear n. In dry climate, the wood of the forearm is apt to chy out and shrink. Occasional applications of raw linseed oil help keep wood in condition. Apply oil to wood only, allow to remain a fe>v hours to be absorbed, t hen wipe off a nd polish with a clean, dry cloth. Exercise care not to a llo"· linseed oil o get into crevices or mechanisms, as it " ·ill "gum up" when dry. 60 AGO 4471B AGO 4471B No te. If reinforcing sc rews are not avai lable through normal supply channels, they can be fabricated a. shown in figure 29. 61 CD .... ("') co .... co i. Loose Escutcheon in F01·earm. If escutcheon becomes loose in wood of forearm and wood is "chewed up" so new eating cannot be made, coat bottom and sides of aperture with plastic natural wood substitute, reseat escutcheon while plastic wood is still moist, and allow to harden before tightening screw. If plastic wood is not available, apply glue or shellac and insert escutcheon. 70. Assembly and Installation a. Assembly of Gas Cylinder and Foreann G1·oup (fig. 26). (1) Using combination tool 7266450 (fig. 4), screw the gas cylinder body into the gas piston tube until tight; unscrew tmtil key notch alines with notch of tube directly beneath t he barrel. Install gas cylinder key (fig. 26) to lock the body to the gas piston. Screw the gas cylinder regulator assembly into the body as far as possib le. Adjust regulator assembly to the setting ob erved at time of disassembly. (2) Snap front swivel bracket back onto tube and, with the bracket swivel in position, install the bracket wive! screw . (3) Install forearm escutcheon and set the gas cylinder tube in position in the forearm. Install the long forearm screw. Position the forearm screw >Yasher and install the short forearm screw. (4) Slide forearm shield into slots in wood, concave face up (aperture to rear for shield of early manufacture). b. I nstallation. Refer to FM 23-15 for installation of gas cylinder and forearm group. I "'"'"' 0 0 I .... ("') ~---g---l .o 0 1111 < cr: .... :.t .,o_ .,u_ .,. · oo ....... o -~a:' ~~ ft - - u UJ "'"'"' "'<Ito. ' V> l "' 0 I I--' ~~~ u UJ :1: ~ < ~ Ci ("') ::::> Vl Vl I CX) ~ w -o u ..... .... ~ w <>' < z 3: Vl Vl z 0 Vi z ~ 0 < cr: -o ~ ~:i: -.... < ~o · / ...J ...J < w f- 0 z ~ ~ N r "'.....- w <>' < z ~ I Vl ' REAR SIGHT ASSEMBLY 71. ("') 0 I 0 Section VIII. co "'..... CD 1 /. CD t;; "- ..0 "- ::::> ........ V> I- -' < ""'Of lm Of ~ou "'..... 0 I I- Vl z 0 Vi z ~ 0 ...J ...J < w bz Removal and Disassembly a. Removal of Rear Sight Assembly From Receiver. R emove the rear sight assembly from receiver by first unscrewing the base setscrew and then, using a block of hardwood, driving the base out of the receiver to the rear (fig. 30). b. Disassembly of Rear Sight Assembly. ole. The key letters shown below in parentheses refer to figure 31. (1) Drive out windage screw knob pin (D) from windage screw knob (E) and remove knob from windage screw. Remove windage screw knob click plunger (G) and spring (F). (2) Unscrew windage screw (A) to the left, and remove leaf assembly (C) and base spring (H) . R emove windage scale screws (J) and windage scale (K) . (3) Drive out elevating screw knob pin (Cl) from elevating screw knob (C2) and remove knob from elevating screw (C3). Remove elevating screw knob click plunger (C4) and spring (C5). Drive out elevating screw retaining pin (C7) and unscrew elevating screw from leaf (C8) . Remove slide (C6) from top front of leaf. · At::() dd'71R I Figw·e 30. 72. A- WINDAGE SCREW~5013160 B-BASE SETSCREW--5013158 C--LEAF ASSY--5564208 1--!ELEV SCREW KNOB PIN-5013166 2--lELEV SCREW KNOB-5152778 3-ELEV SCREW--6147327 4--fELEV SCREW KNOB CLICK PLUNGER-5163398 --{ELEV SCREW KNOB CLICK 5 PLUNGER SPRING5163397 6-SLIDE-5564209 7--lELEV SCREW RETAINING P1N-5013162 B--LEAF-6535422 I ~ ~ 1 2 ;..-:; :-> .:::; e· ~ ,ij 3 c 4 5 Driving 1'ea1· sight base ojJ receiver. Inspection a. Genera l. Inspect parts for damage, exce sive \\'ear, bur , ru L, foreign matter in reces e , deformation, and for free action with mating part ·. lnsp ct . crews and screw ho les for stripped threads. b. Base (JToup. Inspect rear sight base for loo enes on receiver. Inspect windage scale for loosene son ba ·e. In pect pring for weak fwlct ion and fracture. c. W indage Screw GToup . In spect cli ck plunger for fw1ctioning with knob. In pect click plunger spring for functioning and fracture . d. L eaf Group. In ·pect ftmctioning of elevating crew in leaf and with slide. In p ct click plunger for functioning. In. pect screw for missing or loose retainer pin . Inspect plw1ger vring for functimung and fracture . 73. Repair R eplace all broken, worn, or other"·i ·e unserviceable parts. R emove burs and rust a explai ned in paragraphs 35 and 36 . 74. Assembly and Installation Note. a. 64 The key letters shoKn below in parenthe es refer to figure 31. A ssembly of Rem· Sight Assembly. (1) Install lide (CG) in leaf (CS) and in ert elevating sc rew ( '3); then ·ecure in place with th e elevating screw retaining pin (0.512 x 0.200) (C7). Insert el vating screw knob click plunger (C·l-) and pring (0.071-in . 0 D , 5 coi ls) (C5) in hole on top of leaf. Place elevating screw knob (C'2) on elevating sc rew and sec ure with elevating . crew knob pin (0.512 x 0.37) (C l ). D--WINDAGE SCREW KNOB PIN-5013700 E--WINDAGE SCREW KNOB--6008809 F--WINDAGE SCREW KNOB CLICK PLUNGER SPRING-5013154 G--WINDAGE SCREW KNOB CLICK PLUNGER-5013155 H BASE SPRING-(7266108 <SHOWN) -15013157 -.f---WINDAGE SCALE SCREW--5153167 K--WINDAGE SCALE-5013159 7265564 (SHOWNJ L--BASE-- 5564231 { 5613656 RA PD 134744 Figure Jl. Rear sigltt assembly- e.rplocled 1•iew. AGO 4471B AGO 4471B 65 (2) Install base spring (H ) a nd windage scale (K) on sight base (L ); then secure windage scale with two windage scale screws (J). Position leaf assembly (C) and screw windage screw (A) in place. (3) Insert windage screw knob cli ck plunger (G) and spring (0.118in. 0 D, IOY2 coils) (F) in hole in windage lmob screw (E) and place knob on end of windage screw. Secure knob with a windage screw knob pin (0.0635 x %, stght) (D ). b. Installation of Rear Sight Assembly on R eceiver. Drive sight base onto receiver and then e ure with t he base setscrew (B) . 75. FOLLOWER-60 19641 Functional Check a. Check hinge and locking fun ction of leaf assembly with windage screw and base spring. b. Check functioning of elevating and windage crews and click m echanism. c. Check 0 setting of windage scale for front sight al inement (aline by eye) . Section IX. 76. MAGAZINE ASSEMBLY Removal and Disassembly Refer to FM 23- 15 for removal an d elisa. sembly of magazine assembly (fig . 32). 77. Inspection (fig . 32.) a. T ttbe. In spect magazine tube for dents, deformed or burred lips, and worn or burred catch lug. If lug or catch is \YOrn sufficiently to allow magazine to ch·op slightly after insertion, feeding of cartridges may be affected. b. Base. Inspect base for looseness in tube. c. Follower. In spect follower for binding in tube under spring tension. Follower w:itb , pring assembled slides smoothly up and clown tube when depressed and released by a blLmt instrument or cartridges. When inspecting, bear on ent ire top smface of follower , not at one point only . d. Spring. Inspect spring for deformation , fractme, and set. e. Niagazirze and P aTis. Inspect magazine and parts for rust and corrosion and interior of tube for foreign m atter. 78. SPRING-5509077/ / BASE-60 19631 Repair a. The magazine is expendabl e and is replaced as an assembly . Io replacement spare parts a re furnished for repair. b. If catch lug on magazin e is worn to the extent where proper retention is doubtful, scrap the magazine. 66 AGO 4471B RA PO 26562A Figw·e 32 . AGO 4471B Mago zine assembty- e.t]Jloded ••iew. 67 79. Assembly and Installation Hefer to Fl\'I 23- 15 for assembly a nd install a tion of magazine assembly (fig. 32) 0 Section X. 80. BIPOD ASSEMBLY Removal and Disassembly R efer to FM 23 15 for removal and di sas.-e mbly of the bipo l as:::; m bl.v (fig. 33) 0 Inspection (fig. 33) a. fT a ·her, Thwnbscrews, and K eys . Inspect for loose or broken wa her spring on \\·asher body (tack-weldrd). Inspect clamping t humb. crews for tripped threads. In. pect keys for fractLU'e and deformation . b. Body. Inspect bipod body for deformation of cylinder and leglockin g slot · for wear, cracks, and burs. c. BizJocl L egs. Inspect leg joints for looseness on tubes (brazed), loose fi t in body mating apertures, locking action, wear and bm . In pee t ube for deformation and for burs and foreign matter in keyways. d. S liding L eg. (LH and RH) . Inspect clamps for looseness on t ube (brazed), pring action, and stripped or burred threads. Inspect fo r loo e an d deformed feet (welded) . Inspect ·tiding legs for binding or exce sive loosenes on leg tube ; they hould slide freely without binding or shake. I 0~ UJW'<t 81. 82. Repair a. When rebuilding rifl es replace bipod assemblie. of early manufacture (fig. 45) with bipod assemblie. conforming to late. t design (fig. 33): b. R eplace all broken, 'Torn or otherwi ·e un. erviceable part . Remove burs and rust as explained in paragraphs 35 and 3G. 83. o,() -~ ....JC::r-- N o~f;;~ C"'J r-- Oro~ .... r-- ~::EU') Ol::J ;;:; I 1- r-. U') j UJ _J 0 z I ~ w 0 :J Vl ex: u VI (l) ::E ::J I 10 UJ __J 0 0 a. co \ ·~ I r-- ex: C"'J C"'J <; ] r-- .... co f"} I >- -r-N ~ ;;; I co >w 0 l£ 2 d\ ~ f"} 0 0 Ol ""I N 0 w __J (") r-- j UJ __J 0 0 a. w "'"' <:j f'oo. ....., ~ c N N .~ ~ f"} r-- I l9 w _J ~ "":i ~ "" ~ Assembly and Installation Refer to FM 23-15 for a sem bly and installation of the bipod assembly (fig. 33). 84. Functional Check Check bipod as embly for looseness on flash hider (bearing); should be " ·lip on" fit . Check spring washer for functioning with bipod assemb ly. Washer is as embled to barrel with spring forward. Check locking fun ction of t humb. crew , folding and locking action of legs, and locking of ·licling legs. Section XI. CAL .. 30 JOINTED CLEANING ROD M 1 85. Inspection Inspect the cleaning patch ection (fig. 3-J.) of the cal. .30 jointed cleaning rod Ml for deformat ion or other signs of unserviceability. 68 AGO 4471B AGO 4<171B 69 I STRAIGHT PIN - 505247 CHAPTER 5 / r CLEAN ING ROD HANDLE-6147612 ~~ ~ FINAL INSPECTION FIRST SECT ION- 60 17664 ,--------- ----\ SECOND' ,~~-:::o-.... S EC T ION- ~ 6017659] 87. --------------- ~ (- - - - - - - - - - - '~ . ____ , ~~ ---- ----- ________ _,} ~~ --~~~ CLEAN ING PATCH SECTION --6017660 86. Materiel to be returned to use r must meet th e standards and tolerances prescribed in chapter -±. 88. Inspection Guide Table IV is provided a. a guide for the final inspection of weapons after repair and before return to the u er . <.~r RA PO 134745 Figure 34 . General T able IV . Point to be inspected Ji'inal im;prct io n Cal ..30 jointed cleaning rod ~!1 -e.t]Jloded view. FINISH ______ _____ ________ ____ FOREAR:\L _____ ___ ___ __ ___ __ Replacement If the cleaning patch sect ion is unserYiceab le, replace . BUTT STOCK (PLASTIC)__ ___ BORE _________ ________ ___ ____ BREECH BORE __ ___ _____ ____ FRONT SIGHT __ __ ___ ____ ____ REAR SI GHT __ ___ __________ __ HAMMEJ'~ PIN ____ __ ___ ____ _ _ BOLT LOCK ____ ____ _______ ___ BOLT LINK PI ____ __ ____ ___ _ BIPOD ASSY - --- --- - ---- - --- HEADSPACE ______ _______ __ __ PISTON DIA ____ ______ ___ ___ __ SLIDE ASSL __ ___ __ ___ ______ _ GAS CYLI DER DIA ___ _____ _ TRIGGER PULL___ _____ _____ _ FIRING PIN HOLE __ ___ _____ _ FIRING PI I PROTRUSIO I _ _ 70 Final l ns]Jeclion AGO 4471B AGO 4471 B Dull enough to prevent glare. flea soned crack. , sma ll d ent~, a nd insignifi rant cracks are acceptal lc. Cracks that are not at critical points are acceptable. Fine uniform pitting but with sha rp lands is acceptab le. l\fa.ximum 0.306 inch. Use gage 5564343. SecUJ·ely assembled with no burs or malformat ions. l\Iu t be secme on receiver. E levation and windage scales to function smoot hly throughout range. Graduations to he legible. No check. No check ~o check. Refer to figs. 44 and 45 to see if bipod assembly is of la test design. Min.imum 1.940 inch . Use gage 731994-!. l\faximum 1.950 inch . Use gage 7319954-. }Iinimum 0.494 inch. Use gage 5077201. Check fo r out--of-round of ham mer pin hole. Check sear notch for wear. l\laximum 0.503 inch. Use gage 5077204. 1initmun G pounds. Ma.,imum 10 pounds. No chec k. Approximately % inch. I 71 APPENDIX REFERENCES 1. Publication Indexes Department of the Army pamphlets of the 310-series and DA Pam 108- 1 sholllcl be consulted frequently for latest changes or revisions of references given in this appendix and for new publi cation s relat ing to materi el covered in thi publication. 2. Supply Manuals The following manuals of the Department of the \.rmy supply manual pertain o this materiel: a. Destruction to Prevent Enemy se. Ammunition Explosive , Bulk Propella nt: a nd Explosive Devices ____________ ___________ , l\ I 9- 5- 1375 Pyro technics, 1\Iilita.ry, All Type ·________ ___ Sl\I 9- 5- 1370 Land Mines and Components ___ ____________ 81\I 9- 5- 13-1-5 b. General. Index of Supply Manuals; Ordnance Corps __ DA Pam 310- 29 In t rod uction and Index ______ __ ____________ ORD 1 c. Repair and R ebuild. Abra ive , AdhesiYe , Cleaners, Preservative , RecoilFluicls,SpecialOils, andRelatedltems _ Soldering, 1\Ietallizing, Brazing, and W elcling Materials; Ga es and R lated Items ____ ___ Lubricating Equipment, Acces ories, and Related Dispensers ________ __ __ ____________ Misce llaneous H ardware ___ ____ ________ ____ Shop Set, Smail Arm , Field Maintenance ____ Special Tool Sets for Small Arms and Automatic Weapon (S L Group A and B) ____ Standard H ardware ____ __ _________________ Tool Set, Armorers' (l\IOS 0511 ) ____________ Tool Set, Small Arms Repairman (Ordnance) ( 'lOS 0903) ___ _________________________ ORD 3 S L K- 1 ORD 3 S L K- 2 ORD (*) SNL I(-3 ORD 5 SNL H - 2 ORD 6 S JL J-8, Sec. 6 ORD 6 SNL J- 12 ORD 5 SNL H- 1 ORD 6 SNL J- 10, Sec. 1 ORD 6 S JL J- 10, Sec. 2 d. n -eapon. Rifie, Automatic, Cal. .30, BrmYning, 11918A2 ______________________________ ORD (*) 'NL A-! 3. Forms Tb e follow ing form s pertain Lo th is materiel: • ee DA Pam 3 10- 29. Index of Supply ?IJ au uals ; Ordna nce Corp , for published types of manuals of the Ordnance section of the D epu rllll Cll l of the Army su pply manual. 72 DA Form 9- 71 , Locator and luventory Control Card DA Form. 9-77, Job Order R egister DA Form 9- 7 , Job Order DA Form 9- 79, Parts R equi ition DA Form 9- 0, J ()b Order File DA Form 9- 1, Exchange Part of Uni - Identification Tag D Form 421, Stock R ecord Card DA Form 468, Un atisfaetory Equipment R eport DA Form 811 , Work Reque t and J ob Order DA Form 828, Job Tim Ti cket-Individual DA Form 829, Rejection Iemorandum DA Form 865, Work Order DA Form 866, Con olidation of Par ts DA Form 67, Status of Modification ~ ork Order DD Form 6, Report of Damaged or Improper Shipment 4. Other Publications The following publi cations contain information pertinent to this materiel and associated equipment: a. Camouflage. Camouflage, Ba ic Principles ______ ____ ___ ___________ F 'l5- 20 Camouflage of IncliYiduals and Infantry \\capons ______ Fl\I 5-20A b. D econtamination. D econtamination __________________________________ TM 3-220 Defense Against CBR Attack_ ___________ ______ ______ FM 21--10 c. Destruction lo P1·evenl Enemy [.,'se . Explosives and Demolit ion ----------- - - ----------- - FlVI 5-25 Ordl1ance Servi ce in t he Field ______________ _________ _ FM 9-5 d. General . Common Classification Code ______ __________________ Inspection of Ordnance Materiel in t he H and of Troops __ ___ _____ _____________________ ____ ____ __ Accident R eporting ______________ ____ ______________ Unsatisfactory Equipment R eport_ _________ ______ ____ e. Operation. Ftmdamentals of mall rms __________________ ______ Small Arms Hatcriel and Associated Equipment _______ f. Re7Jair and Rebuild. Abrasive, Cleaning, Preserving, Sealing, Adhesive, and R elated Materials Issued for Ordnance 1Iateri eL ___ "' elding Theory and Appli cation _______________ ______ Lubrication _____________________ _______ ___________ R esearch and D evelopme nt, Type Clas ification, i\Iodernization Cod ing, and l\Jodification of MatNiel _ _ ___ Ordnance Maintenance and General Supply in the Field _ AR 711- 50 TM 9-1100 SR 385-10--10 AR 700-3 TM 9-2205 T ti 9-2200 TM 9-850 Tl\I 9-2852 T i\II 9-2835 \ R 705-5 FM 9- 10 AGO 4471B AGO 1471B 73 Painting Instructions for Field Use ______ ________ ___ __ Rebuild Standards for Small Arms MaterieL __________ g. Shipment and Limited Storage. Army Shipping Document_ _________________________ Field Inspection and Servi ceability Standards for Small Arms MaterieL __ ________ _______________________ Ordnance Preservation, · Packaging, Packing, Storage, and Shipping ______________ ___ _____ ______________ Marking of Oversea Supply __________________ _______ Ordnance Storage and Shipment Chart Group A Major Items and Major Combinations of Group A ________ Twin Cal. .50 Machine Gun Pedestal Mounts M46 and M65 ___ __ ____ __ ___ _____ _________________ ________ INDEX TM 9-2851 TB ORD 366 TM 38-705 TB ORD 587 TM 9-1 005 SR 746-30-5 TB 9-CSSC- A TM 9-230 Report of Damaged or Improper Shipment_ ___________ AR 700-58 h. Weapon . Browning Automatic Rifle, Caliber .30, M1918A2 ______ FM 23-15 Packaging of Small Arms Materiel With Volatile Corrosion Inhibitor CVCI) ____ __ __ __ __ __ ____________ __ TB ORD 623 Paragraphs Accidents, field report _________________________________ _ Actuator. (See Butt stock, buffer, and ar tuator group. ) 3 53 18, 51 50 52 39 41 14, 36 32 40 23 83 84 81 80 82 17 68 68 68 68 68 14 57 58 19, 55 54 56 45 45 15, 4! 36 22 62 22, 60 59 61 52 15, 46 46 50 Carbon and rust removaL ________________ --------- - ---Clearling ________________________ ___________ _________ _ Cleaning rod ML ______________________________ ___ ___ _ Cyclic rate mechan ism ______________ _____________ -----_ Cylinder. (See Gas cylinder group. ) 35 33 85, 86 4j 22 21 68, 70 6 Data, tabulated ____ ___ ___________ ____ ___ ------------ -D escription of rifle Ml918A2 _____________________ _____ _ 5 6 3 Barrel and receiver group: Assembl y and installation ___ __ ____________ -- ---- - -_______________ _________ ________ _______ _ In s p ec~on R emoval and disassembly _______________ ---_-- __ --R epair_ _______________________________________ __ _ Barrels, repair ____________________ __ __________ ______ __ Bipod assembly: Assembly and installation _________ ___ ___________ __ _ Functional check _________________ ______________ --Inspection _______________________________________ _ Removal and disassembly ______________________ ___ _ R epair ____________________ ___ ___________________ _ Bipod group, in pection in hands of troop ________ - ___ _-Bolt group: Assemb ly and installation _________ ___ _____________ _ Functional check________________________________ __ Inspection _____ __ __________________________ ______ _ R emoval and disassembly _______________ --------- -R epair_ __________ ___ _____ ______________________ __ Buffer . (See Butt stock, buffer, and actuator group. ) Burs, removal ____________________________ -------- ----Butt tock, buffer, and actuator group: Assemb ly and insta llation _______ _____ ---------- - --In spection _______________________ ___ - - - ---- - ----- R emoval and d isassembly ______________ ------- - ---R epair_ _____________________________ - ------------ Equipment. Gas cylinder and forearm group: Assembly and installation _____ ___________ --- ______ _ Inspection ____________________ __ _______ __ ________ _ AGO 4471B AGO 4471B 4 44 45 (See Tools and equipment.) Final inspection: D escription ______________________________________ _ Instructions (table IV) ______ ______________________ _ Forearm. (See Gas cy linder and forearm group and Stock and forearm gro up .) Forms, record , and reports __________ ------------------Function-fu-ing _____________________ - ------------------ 74 Pages 3c J2d lL 87, 88 71 3 42 3 23 76 23, 68 66 15, 58 75 R emoval a nd disassembly ____ __ ___ _______ ___ ______ _ R epair ____________________________ ____ __________ _ R eaclspace, inspection in ha nds of troops _____ ___________ _ Inspections: Categories ________ _________________________ ______ _ Final _______ ___ _____________________________ ----iVl ateri el: In han ds of Lroops _______ _____ ______ __________ _ Received by ordoan ce shop __________ ______ ____ _ Preemba rkation _________________________________ - _ Purpo e __ __ _____________________________________ _ Scope ___________________________________________ _ Jointed cleaniog rod :\IL _____ __________ ________ ------Lubrication ___ __________ ________ ___ _________ __ __ --- __ _ 67 69 27 12 l2, P-7, 88 56 60 17 ll 11 , 7 l 28, 2!) 12 19 1.8, 19 Jl 11 10 ll 85, 86 68, 70 l :l '27 30, :3 1 33 21 assembl y: Assembly and installation _________________________ _ Inspection _______________________________________ _ Removal and disassembly ____ ____ ___ _______ _______ _ Repair ___ ______________________________________ __ Maintenance allocation ______ ________ _____ ________ ____ _ 7!1 71 76 78 2 68 66 6G Operations route sheet (ta ble III) ___ ____________ _______ _ 43 ~I agaz in e Parts: Inspection __________ ___ __________ __ ________ ______ _ 29 R eplacement _______________ ________ ________ ___ __ __ 3±u R equisitioning ___________________________________ _ 7 Pisto n. (See Sli de a nd piston group. ) Preembarkation inspection ____ ___________________ ------ 12b, 28, 29 R ear sight assembly: A sembly and installation __ _ _____________________ _ Functional check_ __ _______ _____________________ _ I nspection _____________ ________________ __________ _ R emoval and disassembly _______________ _____ -----R epair_ _________________________ - ________ --- - --- R eceiver. (See Barrel and receiver group.) R ecords and reports __________________________________ _ R epair _______ ____________________________________ ---R epair m ethods ______________________________________ _ Rifle inspection i n hands of troops ______________________ _ Riveting _______ ___ _____ ____________________ _____ ____ _ Ru st removaL _______________________________________ _ Safeties _____________________________________________ _ Scope___ _______ __________________________________ ___ _ Sig hts, inspection in hands of troops ____________________ _ Slide and piston group: Assemb ly and installation _________________________ _ Inspection __________ _____________________________ _ Removal and elisa sembly _________________________ _ Repair_ ______________ - ____________________ ------Springs, repair ____________ ______ _____________________ _ Stock and forearm group, inspection in hands of troops ___ _ 76 7-± 75 72 71 73 3 32- 86 3± 15 66 2 24 19 22 7 11, 18, 19 71 J3 2J 9 7 31 5 34e 19 6 22 8 7 26, 29 17, 19 9 3d 34c 7 3 47 4-± ±8 21, 45 ±9 4± 46 25 31 22 30 25 31 15, 25 32 25 29 16 19 Unsatisfactory equipment report _______________ ____ - _--- 3d 3 \Velcling __ ____ ___ __ ___ - ------------------------------\\"ooclen components, repair_ ___ _____ -------------------- 3-±d 22 23 37 3 21 23 2 14 66 56 15, 52 52 56 2:l 16 2± 88 6± 41 1 16 40 Trigger guard assembly: Assembly ______ ____ ___ _________________ __ _____ ___ _ Disassembly ________ __ _____________________ ______ _ Functional check____ ______________________ _______ _ Inspection _____ _______ _____________________ ______ _ Installation _________ ________________ ---- - -------- R emoval ________________________________________ _ Repair ___________________________________ __ __ ---Trigger pull, inspection in hands of troops ______ _________ _ Troubleshooting (table II ) ___________________ ___ ______ __ 22 23 GG 6± 63 35 20, G± 6:3 65 T ab les: Final inspection (table IV ) ________________________ _ Operations route sheet for ca l. .30 Bro1miJ1g automatic rifle J\Il918A2 (table 111 )_ ________________ _______ _ Special tools and equipmenL for field maintenance (table I ) ___ _____ _____________________________ - _ Troub leshooting (table II )_ ____ ____________ ------ --Tabulated data __________ __ __________________________ _ Threads, repair_ _____________________________ ---- - - - -Too ls an d equipment: Common ______ __________________________ ________ _ Inspection ___ _____ _______________ __________ ____ __ _ Specia l (table I ) __________________________________ _ nsatisfactory eq uipment report_ __________________ _ Use of tools ______________________ _____ ________ ___ _ 38 3-±.f 6~ 2 1. 1:3 22 22 34d Surfaces, repair : Finished _________________ --- ______________ ___ ---Machined and polished _____ ____________ ___ ________ _ AGO 4471B AGO 4471B 77 [AG 474.2 (28 Jan. 57)] BY ORDER OF THE E RET ARIES OF THE ARi\IT A 1 D THE AIR FORCE: MAXWELL D. T YLOR, General United , late Army. Chief of taff. OFFICIAL: HERBERT M. JONE , Major General, United State Army, The Adjutant General. N. F. TWINING , OFFICIAL: Chief of Sta:f)", [ nited tales Air Force. HARLES M. McDERlVIOTT Colonel, [;nited Stales Air Force, Acting Air Adjutant General. Di ·tribution: Aclit•e .lrmy: C GB Pl\IST r Div Ord nits Orel Ammo Comd Gen Depot Orcl Sec, Gen Depot Orel Depots POE (OS) Trans Terminal Cornel Army Termin al 0 up Agencie Orcl PG Ord Arsenal i\lil Di t Ord Proc Dist l\IIAAG i\[j I l\llsn JBUSJ\IC JUSi\IAG (Greece) Fld Comd, AFSWP ASA Tee Svc, DA Orel Bel Hq CO~ARC CO~ ARC Bel Army AA Cornel 0 ;\laj Cornel OS Ba, e Cornel Log Cornel i\lD\V Armies Corp Div Orel Gp Orel Bn Ord Co Ft.& Cp Gen & Br vc cb XG: 'late AG ; units-smne as Active Army. S tlR: Xone. For expla nation of abbreviation used, see R 320- 50- l. U.S. GOVERNMENT PRINTING OFFICE· 19S7-400SZO 78 AGO 4471B