Air Rifle Repair Manual

Air Rifle Repair Manual
Revision 4.3
Copyright 2015, All Rights Reserved, UJ Backus
This Manual is intended to be a guide for those seeking information on the repair of Sheridan air rifles.
It is not instructional material and only those who have proper skills should attempt repairs.
The Author therefore assumes no responsibility.
Index
Preface.............................................................................................................................................3
Model A and B (Super-Grade and Sporter)....................................................................................3
Model A and B operation and maintenance....................................................................................4
Model A and B piston / pump cup..................................................................................................6
Model A and B valve removal.........................................................................................................9
Model C and C-SERIES (Silver Streak and Blue Streak).............................................................12
Pneumatic rifle pump cup replacement..........................................................................................13
Pneumatic rifle valve seals replacement........................................................................................17
Model F and F-SERIES (CO2 Silver Streak and CO2 Blue Streak)..............................................23
CO2 rifle valve seals replacement...................................................................................................23
Model C9-SERIES and F9-SERIES...............................................................................................26
Cartridge valve seals replacement..................................................................................................28
Part numbers...................................................................................................................................29
A note on barrel separation.............................................................................................................30
Tranquilizer guns and paintball markers........................................................................................30
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Preface
An understanding of the mechanics of air guns is necessary in order to perform repairs properly and
safely. Sheridan air guns are of the pneumatic type and the CO2 gas type. Care must be taken during
disassembly and all parts cleaned with a proper solvent. Alcohol is adequate for most parts. Lacquer thinner
and #0000 steel wool can be used to remove heavier grunge and stains. For re-assembly, light grease and
non-detergent oil should be used sparingly in the proper places. A 50/50 mix of 30wt non-detergent motor
oil and Marvel Mystery oil works well. Keep in mind that the barrel and air tube are made of brass
compounds that have self-lubricating properties. The bore need only be cleaned with alcohol and a soft
cloth patch. Wood should be carefully cleaned and preserved with light oil. Several products are available
that can restore the wood to a presentable condition without destroying its originality. Formby’s Lemon Oil
Treatment and Birchwood Casey Tru-Oil give good results. To preserve collector value, re-finishing should
be avoided unless it is deemed necessary due to excessive wear and/or damage.
The text and photos in this manual will guide the individual in the repair of Sheridan air rifles.
Replacement parts, as well as the special tools needed, are available through several sources which can be
searched out on the Internet. The exception is the Super-Grade and Sporter. Although replacing the pump
cup is fairly easy and requires no special tools, replacement pump cups are not readily available. Repair of
the valve is difficult, parts are scarce, and special tools are required. Therefore, it is best to send these
models to a qualified airgun smith.
When properly repaired a Sheridan air rifle will last for many years. The owner’s Hand Book for the
particular model is a valuable source of information on operating, care, and maintenance. Originals and
copies are occasionally listed on the various auction sites found on the Internet.
Super-Grade and Sporter
Model A pneumatic rifle / Model B is basically the same
These models were manufactured from 1947 to 1953
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Model A and B operation and maintenance
This information is taken from the owner’s Hand Book
Operation
Open bolt and draw back slightly until it stops against the main spring. Pull bolt back hard against spring
until sear engages with a “click”. Bolt is now free and should be closed again so that safety lever can be
operated. Do not jamb bolt handle down hard when closing. The front of the bolt provides a tight seal in the
barrel when it is closed with very little pressure.
Move safety lever to rear to put on “Safe” and forward again for “Fire”. The safety can only be operated
when the rifle is cocked as described above.
Charge the rifle with the desired number of pumps. As with the operation of the safety, the rifle can only
be charged when cocked.
Open bolt and insert bullet (pellet) into chamber at rear of barrel. Push bolt forward forcing bullet
(pellet) into rifling and close bolt. Again, as described above, do not jamb bolt handle down too hard. This
saves the camming surface on the receiver from unnecessary excess wear.
Shoulder rifle, take aim at target, move safety to “Fire” and squeeze trigger. FOLLOW ALL SAFETY
RULES.
Valves
In a pneumatic rifle dirt on the valves or valve seats will naturally cause air leakage. The Sheridan is
constructed so that it can be “blown out”. That failing to remove the dirt (in case of a gummy sludge) it can
even be washed out without taking the mechanism apart.
1. To blow out the valves, merely pump rifle two or three strokes without cocking the action. Make sure
before doing this however that there is no bullet in the chamber.
2. To wash out the valves, raise pump lever to top of stroke and squirt a drop or two of light oil in the
small air intake hole in the pump tube and (also with action not cocked and rifle unloaded) work the
piston to blow oil and dirt on through. This will also lubricate and prevent rust on such internal action
parts as valves, firing pin, striker, etc. After doing so, shoot rifle a few times unloaded and against
something the oily blast of air cannot spoil. The oil fouling in the barrel should also be cleaned out to
retain top velocity and accuracy.
Model A and B valve unit components
4
Do not think valves are dirty or leaking if the pressure developed by one or two pumps is not retained in
the air chamber over a lengthy period. To withstand pressures up to half a ton, which may be built up in a
Sheridan, it is advisable pneumatic engineering not to use a soft valve-seat that would readily seal a few
pounds of air, but not hold the higher pressures.........No practical shooting is attempted with only one
pump, and two or more will provide sufficient air pressure against the hard and sturdy valves to seal the
chamber.
When your Sheridan is not used regularly.......you may encounter normal slight seepage. It will
disappear with use – or if the rifle has become extremely dry – with a drop or two of light oil in the air
intake hole under the pump lever forced through the valves, by pumping with the action not cocked, in the
same manner dirt is washed out.................If slightly dry and seeping, a heavy charge of half a dozen strokes
left in overnight will usually completely seal up the chamber.
Dismantling
1. To adjust trigger pull: Remove stock by pushing out safety lever pin and taking out safety lever
(Model A only). Then remove forward and rear receiver screws (the two large screws on the
underside of the stock). Open pumping arm slightly, and carefully remove action from stock. Pull can
be adjusted by changing the position of the sear spring on the notched tang. Move backward to
lighten and forward to increase weight.
2. To adjust bolt handle: The locking taper between bolt and handle allows one to set the later were
preferred. Keep in mind however that the front end of the bolt body is also a needle valve to eliminate
leakage behind the bullet. If bolt handle is adjusted so low that it can strike the wood before needle
valve is in position, it will not form a proper seal. To change position of handle, loosen screw (on end
of bolt) with large screwdriver. Tap (bolt handle) loose and turn to desired position. Retighten
(screw) very firmly to avoid slippage.
3. To clean pump tube: Remove piston assembly by starting with screw on nose of muzzle cap. When
this is out, raise pump lever slightly and tap out pivot pin. Remove the two muzzle cap screws, and
using a piece of wood tap off the muzzle cap. This allows whole assembly to be withdrawn. A
cleaning rod with a good sized cloth over the end works well to clean out the tube. Wipe off and
lubricate piston and cross head. Also put a drop of oil in all working points (pivots), and one in the
long slot of the pump lever for the leaf spring.
Tips on Re-Assembly
When replacing stock on action raise pumping arm slightly and action will slip into place readily. The
longer of the two stock screws goes in the back of the trigger guard. Do not reverse them.
(Model A only) The safety lever is put in from the small slot in the safety lever plate so that the ball on
the bottom of the lever is in the hole in the safety slide. When this is in place, move lever back or forward
until cross holes line up, and push in pin. If lever slips in handling twist a narrow strip of tape around the
very top (of lever) to hold onto.
See Supplement B to this manual for removing Model A stock and safety components.
5
Controlled Power
Controlled power makes a really fine pneumatic a very practical rifle to own. For target practice in the
average length basement, three strokes of the piston are sufficient for accuracy. Outdoors at around twenty
five yards, five or six strokes should be ample for general use. Velocity and point of impact can be
regulated for target work, hunting, plinking, etc., by the number of pumps and how they are handled, fast or
slowly. It is always sensible to use no more power than is needed for the job.
Important
Do not put in over eight pumps because the rifle is designed to operate most efficiently with moderate
charges. Do not over-charge and possibly cause an over-heated piston head, scorched valves, or air lock.
The muzzle velocity with eight pumps of the efficient piston is more than necessary or practical for the use
to which a pneumatic rifle is adapted (note: muzzle velocity with eight pumps averages 650-700 fps).
Model A and B piston / pump cup
To check condition of piston (pump cup) remove piston assembly (pump lever/rod assembly) as
described in Dismantling 3 on page 5.
Photo below shows early style assembly at top and later style at bottom. Original piston is made of hycar
cup molded over metal insert.
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take note of measurement to end of cup
piston is screwed onto rod and held secure with lock washer
The original piston can often-times be rejuvenated. Coat the piston in oil and place in a vice with a flat
metal piece on both ends to protect it. Tighten vice so that the end of the cup flares out slightly. Leave in
vice overnight. When removed from vice the cup should remain flared. Follow steps on next page to reinstall piston in rifle and check operation of pump. If the piston cannot be rejuvenated do not discard as it
can be used in the fabrication of a replacement.
See Supplement A to this manual for an example of fabricating a replacement piston.
If the piston/pump rod assembly has been taken apart for any reason, re-assemble to length as noted
above. Maximum power can be achieved by loosening lock nut and adjusting pump rod for slight over
travel (see definition on page 16) at end of pump stroke.
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clean inside of air tube before re-assembly
lubricate piston and pump lever joints
re-assemble in reverse order
8
Model A and B valve removal
To remove the valve unit, first remove the stock as described in Dismantling 1 on page 5. The piston
assembly must also be removed as previously described.
Remove the safety components as shown above. On left is Model A with safety slide, detent and detent
spring removed. On right is Model B with safety lever pin removed, after which lever can be lifted out and
safety slide can be removed. Note that Model B has no detent and spring.
remove pin securing trigger/sear assembly to receiver
Note: this assembly is under slight pressure from the adjustable u-shaped metal sear spring.
USE CAUTION in the next step as the end cap is under pressure from the striker spring.
Remove the two end cap screws and the cap should be pushed out by the force of the spring. Some caps
may be difficult to remove due to a tight fit. A punch can be inserted through the sear slot at the bottom of
the receiver to tap the cap off. Again, USE CAUTION since the cap is under pressure.
The inside of the receiver can be lightly filed if necessary so that the cap is easier fitted when reassembled, but still snug.
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with end cap removed the bolt, striker and spring can be withdrawn from the receiver
There are two types of valve unit retainer nuts. The most prevalent have four notches and the other type
has four circular holes. Pictured are the tools needed to remove each style of nut. The tool at the top is
made from an 11/16” deep socket.
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Remove the valve unit retainer nut then drive the valve unit out of the receiver. This can be done with a
wooden dowel. It helps to loosen the valve unit by spraying penetrating oil down the tube, from the inlet
side, and letting it sit for a while. If necessary, a 9/16” socket on a long extension can be used to knock the
valve unit loose.
USE CAUTION when loosening the retainer nut to not break or damage the safety housing on the rear
of receiver and use a block of wood as shown below when driving out the valve unit.
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Photo on left shows screen on inlet side of valve unit; take care not to damage when removing unit from
receiver. Once the valve unit is removed it can be sent out to an experienced airgun smith for re-building.
Photo on right shows procedure for re-installing valve unit. Use a new valve body quad seal, or properly
sized o-ring, and make sure that exhaust port faces up. The installation tool shown is convenient but not
necessary.
Receiver, air tube, bolt, trigger/sear, safety components and other parts should be cleaned. Apply
oil/lube in proper areas (bolt, trigger/sear, safety, etc.) upon re-assembly.
Silver Streak and Blue Streak
Model C and C-SERIES pneumatic rifle
These models were manufactured from 1949 to 1990
Repairs are outlined in the following Pneumatic rifle procedures
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Pneumatic rifle pump cup replacement
drive out the two roll pins from front of air tube and remove muzzle cap
cross head pin pushes out through roll pin hole
this pin secures the pump arm linkage to the pump rod cross head
13
withdraw pump rod from air tube
clean all parts including inside of air tube
14
there are three styles of pump rods
top is adjustable with pump cup molded into piston head used to about 1961
middle is adjustable with pump cup press fitted in piston head used to 1964
bottom is non-adjustable with press fitted pump cup used to end of production
remove old pump cup
molded in style unscrews and is replaced with custom piston head
Helpful hint: press fitted type are often brittle and can be burned out with propane torch
15
new pump cups are of the press fitted type
top shows pre 1962 original piston head with molded in pump cup
bottom is custom piston head for pre 1962 which accepts press fitted pump cup
oil perimeter of new pump cup to aid in pressing it into the piston head recess
with new pump cup installed and lightly oiled, insert pump rod into air tube
adjustable rods can be set to length for slight over travel*, which requires trial and error fitting
this reduces space between pump cup and inlet valve which will result in maximum power
re-install pump arm linkage and cross head pin
re-install muzzle cap and press the roll pins in with a vise
apply light oil at cross head, pump lever pivot, and pump lever arm at muzzle cap
*Definition: slight over travel is achieved when piston is felt to bottom out during pump arm closure and
the pump arm is about 1/2” from being fully closed.
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Pneumatic rifle valve seals replacement
remove trigger/sear and spring by driving out retention pin
some have a small spring guide pin as shown below
drive out end cap retention pin
CAUTION: end cap is under pressure from striker spring
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some persuasion may be necessary to remove end cap
CAUTION: end cap is under pressure from striker spring
earlier models use three screws to retain end cap
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remove striker, spring, and guide / earliest style striker is shown on left
note ring on second striker from left; many have just half a ring which faces down when installed
1979 – 1990 C-Series rifles with double sear trigger have strikers with two rings as shown on right. Very
late strikers will have a slot which mates to a guide pin pressed into the end cap (see photo on page 27).
Also, the rocker safety on very late end caps may incorporate a detent ball and spring.
typical tools needed to remove valve components
tool at bottom screws onto threads at end of valve body, which are 9/32-32
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remove valve retainer nut and then valve body / the remainder of the valve parts should fall out
sometimes it is necessary to push the parts out with a stiff wire inserted from the inlet side
be sure to remove the valve body seal, which is usually stuck inside the chamber, and clean the seating area
the surface in the bottom of chamber where the inlet valve seats should also be carefully cleaned
Helpful hint: fine sandpaper glued to end of 3/8” X 10” wooden dowel can be used to polish inlet valve seat
assembly order of valve components
new inlet valve, exhaust valve, and valve body seal shown at top
early valve components with original valves and seals shown at bottom
some rifles use two washers / valve body seal can be either lead or rubber
clean and inspect all parts / exhaust valve seat can be polished with #0000 steel wool
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clean inside of tube, air chamber, and chamber threads
make sure retainer nut screws easily into chamber
Helpful hint: tap for chamber threads can be made by cutting slots in a spare steel retainer nut as shown
apply a light coat of oil to surface of seals
drop inlet valve, inlet valve spring, washer(s), and exhaust valve spring into chamber
small end of exhaust valve spring faces base of exhaust valve / refer to photo on previous page
early valve bodies have a single exhaust port; later valve bodies have two or four exhaust ports
be sure to properly align the early single port valve bodies / they have a tab that fits a slot in the chamber
install valve body with seal and exhaust valve as shown / take care to not cross-thread retainer nut
Helpful hint: 1) With exhaust valve components stacked on the tool as pictured, insert into tube and push
down to engage threads.
2) Raise air tube to vertical position on work bench and rotate tube while holding pressure on
tool to start retainer nut.
Note: Retainer nut lead seal is omitted in photo. If blow back is evident when firing rifle and bolt-to-breech
seal is properly adjusted (see bottom of next page), then retainer nut lead seal should be installed.
21
install striker (half ring down if applicable), striker spring, spring guide, end cap and trigger/sear
Note: some rifles have an apparent coat of grease on the striker applied by the factory. This should be
thoroughly cleaned and, if anything, a drop of light oil distributed on the surface. Apply a light coat of
grease or drop of oil on the area where the trigger/sear attaches to the end cap.
tools needed to remove bolt if required
take care to not loose bolt tension spring when withdrawing bolt from receiver
1951 to 1955 bolts also have a small pin that must be driven out before removing cocking lug
the receiver on these rifles will have a small hole on right side that aligns with pin
drive pin out from left side of receiver after removing locking cam and cover
Note: Bolt should seal breech when closed. Adjustment is made by moving locking cam forward or to the
rear as necessary. Bolt handle should not contact stock in closed position when properly adjusted. If
applicable, replace damaged or worn o-ring on bolt loading probe with size AS568-004.
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CO2 Silver Streak and CO2 Blue Streak
Model F and F-SERIES CO2 rifle
These models were manufactured from 1975 to 1990
CO2 rifle valve seals replacement
remove trigger/sear, end cap, striker and spring, retainer nut and valve body as outlined for pneumatic rifles
valve components
chamber plug has a slotted sleeve attached
larger chamber sleeve is made of brass / valve body seal is rubber
retainer nut seal is lead and can be omitted if no blow back is noted as outlined for pneumatic rifles
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insert spent CO2 cartridge and tap with wooden dowel to work chamber plug loose from tube
spraying penetrating oil down the tube may help loosen the chamber plug if stuck
a slight movement of the dowel will be noted when the chamber plug breaks loose
CAUTION: see note at top of next page before proceeding with this step
remove spent cartridge and use a 1/4” rod to drive chamber plug and sleeve out rear of tube
clean all parts, inside of tube, and chamber threads as outlined for pneumatic rifles
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Note: the 1/4” rod used to drive out the chamber plug fits into the face seal cavity in the end of the plug.
Take care to not damage the cavity sides while driving out the plug.
this shows the old seals, and the chamber plug and valve body with new seals installed
apply a light coat of oil on chamber plug o-ring and valve body seal
re-install valve components in tube as shown
complete re-assembly with installation of striker, striker spring and guide, end cap, and trigger/sear
refer to pneumatic rifle section, page 21-22, for helpful notes on re-assembly and bolt removal/adjustment
25
C9-SERIES and F9-SERIES
These models were manufactured from 1991 to end of production
Pump cup replacement for the C9-SERIES is the same as described previously (page 13). Valve seals
replacement for the C9-SERIES and F9-SERIES rifles made before 1995 is also the same as described
previously (page 17 and page 23), except for the trigger/safety assembly which is shown in the following
F9A procedures.
The following procedures also show the removable cartridge valve found in 1995 and newer models.
Model F9A-SERIES CO2 rifle
remove trigger spring components
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drive out trigger/sear retention pin and remove safety components
Note: retention pin has knurled end and must be driven out from proper direction
take care to not loose safety detent ball and safety spring located in end cap
remove three screws securing end cap and withdraw cap, striker and spring from tube
Note: bolt removal/adjustment is the same as previous series except that a 7/64” allen wrench is needed to
remove cocking lug and there is no tension spring in the bolt.
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Cartridge valve seals replacement
remove stock lug, which also serves to secure cartridge valve in tube
drive out cartridge valve assembly with wooden dowel
Note: in pneumatic rifles the cartridge can sometimes be blown out by activating the pump
CO2 cartridge valve components shown at top
pneumatic cartridge valve components with o-rings installed shown at bottom
unscrew valve body and clean parts; re-assemble cartridge with new seals and o-rings
apply a light coat of oil on the o-rings
install cartridge in air tube and re-assemble rifle in reverse order
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Part Numbers
pre 1995 pneumatic rifle part numbers:
pump cup
inlet valve
exhaust valve
valve body seal
valve body
lead seal
valve retainer nut
397-025
10010
397-038
68AT-035
68AT-033
68AT-032
68AT-034
pre 1995 CO2 rifle part numbers:
chamber plug
chamber plug o-ring
chamber plug sleeve
chamber sleeve
face seal
valve spring
exhaust valve
valve body seal
valve body
lead seal
valve retainer nut
F500
F500-0
F500-1
F500-2
G397-012
G397-011
FX505-3
same as pneumatic rifle
same as pneumatic rifle
same as pneumatic rifle
same as pneumatic rifle
pneumatic cartridge valve part numbers:
complete valve assy
exhaust valve body
exhaust valve body o-ring
exhaust valve
valve spring
inlet valve body
inlet valve body inner o-ring
inlet valve body outer o-ring
check valve
397-032
397-033
397-036
397-038
397-035
397-034
397-037
JTX-080
1322-056
CO2 cartridge valve part numbers:
complete valve assy
exhaust valve body
exhaust valve body o-ring
exhaust valve
valve spring
inlet valve body
inlet valve body inner o-ring
inlet valve body outer o-ring
face seal
piercing stem guide
G397-008
397-033
397-036
2250-016
788-061
G397-009
397-037
397-040
G397-012
G397-010
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Barrel separation
A common issue with Sheridan pellet rifles, other than the Model A Super-Grade, is barrel separation.
The solder joint along the barrel and air tube can break due to stress or age. It is well known that the clip-on
rear sight used on 1971 and later pellet rifles can cause stress on the solder joint. An improperly attached
scope mount can also cause stress on the joint.
To check for barrel separation shine a bright light along the barrel/air tube seam and note if any light
passes through the solder joint. Also, pinch between the muzzle and air tube to check for separation at the
front sight. In some cases the receiver can become separated so check that it cannot be lifted from the air
tube.
Barrel separation can be repaired by anyone who has good soldering skills. In most cases the heat
applied will not damage the nickel finish on a Silver Streak. However, the repair area on a Blue Streak may
need to be re-finished.
In the case of minor separation caused by the clip-on rear sight, it is advised to remove the sight to
prevent the separation from worsening. There are different methods to remove the sight. One way is to tap
it from front to rear while holding the wedges stationary so that the sight can slide off of them. If it is
desired to retain the open rear sight installed with the metal wedges, the solder joint will need to be
repaired. The clip-on sight can also be installed using a pair of wedges fabricated from plastic. An
advantage to using plastic wedges is that the solder joint may not have to be repaired. Another option is to
install a Williams 5D-SH or No.64 receiver sight. The bolt will have to be removed to drill and tap the
holes for the two 6-48 screws which secure the Williams sight to the receiver.
Tranquilizer guns and paintball markers
Except for removal of the bolt, repairs for the Model G and later tranquilizer guns and the K-SERIES
paintball markers are basically the same as pellet rifles from the same era.
On tranquilizer guns the cocking handle is screwed directly into the striker. The handle must be removed
to withdraw the striker from the tube when servicing the valve. The swing-open loading bolt on later style
guns does not normally need to be removed for cleaning or o-ring replacement.
Model 176B shown with loading bolt in open position
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On K2 with the bolt closed remove the cocking lug from left side. Bolt can now be withdrawn from rear.
On KP2 remove stock to clear pump handle. Push pump rod up to rotate bolt clockwise so cocking lug is
accessible for removal.
Withdraw bolt taking care to not loose spring loaded detent ball(s). Bolt unscrews from pump rod.
Note: some bolts are secured to pump rod with set screw and can be withdrawn with stock in place.
31
On KP3 and KP2-DF with quick change bolt; pull knurled knob on rear of bolt and withdraw pump rod
from bolt. Turn bolt clockwise so cocking lug protrudes through slot on left of tube. Depress spring loaded
lug into bolt and slide bolt out to the rear.
Note: detent balls remain secure in bolt assembly.
Run cleaning patch through tube when bolt is removed.
Lightly oil bolt o-rings to aid in re-installing bolt into tube.
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To learn more about Sheridan air guns refer to the following books:
“SHERIDAN / Classic American Air Rifles” by UJ Backus
“Know Your Sheridan Rifles & Pistols” by Ronald E. Elbe
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