Sten MKII Machine Plans

The
STEN
MKII
Complete machine plans
STEN SUBMACHINE GUN, 9-millimetre submachine gun that
became the standard such weapon in the British Commonwealth
armed forces during World War II. Moreover, hundreds of thousands
of Sten guns were provided to underground movements everywhere
in Europe during that war. The gun was so ubiquitous that its name
became all but a generic term for submachine gun. The Sten gun
remained in service until the late 1950s.
The most common version of the Sten gun was 30 inches (76.2 cm)
long with a barrel of 7.5 inches (19 cm). It fired at a rate of 550
rounds per minute, and it had a 32-round box magazine that,
however, tended to jam if more than 30 rounds were loaded. The butt
was a steel frame that, with the barrel, could be removed without
difficulty so that the disassembled weapon could be easily hidden.
Its weight was just over six pounds (2.7 kg) unloaded.
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Sten Mk II
PARTS LIST
1.
2.
Barre I
4.
Barrel sleeve
Barre I sleeve lock
Barre 1 sleeve lock spring
5.
6.
7.
8.
sight
Barrel bushing
Receiver tube
Receiver cap
3
l
Front
Trigger housing
9
lb. Butt stock assembly:
:
i
11. Magazine
12. Magazine
13. Magazine
14. Magazine
15. Magazine
16.
17.
18.
19.
20.
21.
22.
23.
syring
26. Sear
27. Bolt
Firing pin
29. Extractor
30. Extractor spring
31. Extractor p i n
32.
28.
stock t u b i n g
butt plate
stock grip
stock ring
housing
housing spacer
housing spacer screw
latch
latch spring
Trigger
Trigger spring
Trigger pin
Disconnector
24. Sear
25. Sear
33.
34.
35.
36.
37.
38.
39.
40.
41.
Closing spring
Closing spring cup
Trigger housing cover
TrigF: housing cover screw (2)
Magazine houskg
Magazine follower
Magazine spring
Magazine spring latch
Magazine botiom
42. Rear
sight
Disconnector pin
Selector
Selector spring
NOTES:
1 . Bolt stopping surface on barrel is lmm f o r -
Selector plunger (2)
2.
ward of magazine well slot.
Bolt stroke is 135mm.
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Receiver tube
Material: seamless steel tubing
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1.5R typ.
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Main spring cap
Material: Imm stock
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Scale: 1 : 1
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------__-
151‘
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Receiver rear end b u s h i n g
Material: AISI 1010 or equivalent
Scale: 1 : 1
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20R
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2.5
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Barrel hushing
Material: 4140
Scale:
Barrel sleeve
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minor 0 29.00
21R
/
Rear sight
Barrel sleeve latch
Note: Stake at assembly
with magazine housing
Magazine housing
Material: as notted
Scale: 1 : 1
78
-
1
r--r
2 3 ‘*
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7
*
70
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-5 -
5
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II
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14.5
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1
ISteel stc. 2.7 ref.
/- Weld
.O ref.
1
29.4
--b-j
Magazine latch
. Material: AISI 1010 or equivalent
2.7mm stock. Case harden O.lmm deep
Scale: 1 : 1
[- 9.5
4 71
11 T \ \ 3R typ.
r
6 .3
I
4.3
+==7.2
Magazine housing spacer
Material: AISI 1010 or equivalent
3mm stock. Heat treat: none
Scale: 1 : 1
/
7’:
23
I
&O-32 drill &
Barrel
Material: AISI 4140
Harden to: Br 255-277
1
56
,
b
- _ - - _- -
A_
-__..-- -_ _.
)--_ -
1
23 d
28 ~4
4.6 --J
1 . 3 2 + .05 -
9.65 + .05
+ .03
!
’ITwist: 1 /250mm RI-I
6
of
Number
grooves:
Groove width: 2.5 + .02
Bore diameter: 8.M + .02
Rifling diameter: 9.06 + -05
1s 75 + _ 02 _~--.--__ .- -.
__I__
_________-.__
----- 22 -80 rpf_
_____
.
1
b
.
STEN Mk II SPECIFICA-TIONS
1.
Cartridge:
9mm Parabellum
Bullet weight
Powder weight
Muzzle veiocity
‘116 grains
6 grains
1400 ft./set.
2. Recoil Spring:
W ire diameter
Spring OD
Active coils
Free length
Initial length
Finai length
Work stroke
0.067 in,
1.00 in.
15
9.40 in.
6.80 in.
3.20 in.
3.60 in.
3.
Weight
(including extractor)
Cocking handle
1.327 ib. (9290 grains)
Bolt:
0.077 lb. (540 grains)
1.404 lb. (9830 grains)
Total recoiling w e i g h t :
Bolt maximum dia.
Bolt overall dia.
Bolt body length
1.381 in.
5.75 in.
4.21 in.
S U G G E S T E D S T E N M A N U F A C T U R I N G NiODIFiCATIONS
1.
Select suitable lightwall steel tubing which is
commercially available. For example, a -fence
p o s t p i p e ( g a l v a n i z e d ) is 38.5mm O D a n d
35.0mm ID, most suitable for use as a receive:.
8.
against ‘birt entering the trigger assembly.
T h i s ccJ<er can be eliminated or made from
plastic.
9J.
2.
Eliminate barrei sleeve.
3.
Weld barrel bushing into the front end of the
receiver for simple, permanent assembly.
4.
Turn barrel blank OD (outside diameter)
without any shoulder, fit the barrel in the
bushing by sliding fit.
5.
Fasten the barrel in the bushing
by two roll
pins of 3/16” diameter, or equivalent.
6.
Turn the bolt OD to fit the receiver ID.
7.
The external portion of the c o c k i n g h a n d l e
(sticking out of the receiver) may be a straight
8.8mm OD, the same as the inside.
The trigaer housing cover acts only as a guard
Ati pins can be roll pins of standard commerciai size, or pieces of drill rod.
13. All springs can be of a standard commercial
.
size.
11. Trigger material may be aluminum or plastic,
side t a b s m a y b e r e p l a c e d b y s p a c e r s o r
washers to keep the trigger located neutrally.
12. l-7/4” diameter nominal size galvanized pipe,
schedule 40 is suitable for a modified receiver:
42.2mm
3D
ID::
35.05mm
YVaII thickness:
3.55mm
Ncte:
A 1” galvanized pipe fits loosely inside a l-1/4” pipe and can be welded
as a filler-spacer where needed,
Extractor
Material: AISI 1040 or equiv., stock 4.7 wide
Scale: 4.5 : 1
harden to: Rc 48-52
W\ / 21
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0
&5R
1 \
Bolt handle
S c a l e : 37 : 1
Material : mild steel
Heat treat: none
59.
4 1 . 5
, I
2
‘-16R
Selector
S c a l e : .a7 : 1
?Aateria!: mi!d steel
Heat treat : none
Trigger housing cover
Material: lmm stock, formed
Required: 1
Scale: 1 : 1
22
142
c------
8 0
tt
39
A11 Sten screws are lo-32 thread, round head type. Trigger housing
screws (2) are 13mm long.
.
.
-.
Trigger housing
S c a l e : .87 : 1
&Iaterial: 2.5mm s t o c k
Rewired: 2
-r
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-7-
42
25
-7
- I -
30
L 16.5rj
\
1
&-
Material: 2.5mm stock
Required: 1 each
xote:
5.5 R ref.
3.1 # wire
C.WR
PINS (Spring pins)
USE
Extractor
Sear
Trigger pin may be substituted by
spring pin 3.1 # by 26 long.
DIAMETER
2.5
5.5
LENGTH
25
24
Firing pin
Material: Drill rod
Harden to Rc 50
SPRINGS
USE
SUBSTITUTE”:
Extractor
1
7 .1
12
%.
LC-04oc-4
Magazine latch
1
8 .7
15.5
Gr .
LC-OLZOC-6
Closing
1.6
26.5
245
sq . -
Trigger
0 .7
4.6
57
Selector
Barrel sleeve latch
Extension
spring
LE-026B-7
or
loops
LE-026C-8
0.45
4 .6
14
Gr .
1
8 .7
35
Sq.
LC-Oi8B-6
Sear spring, formed
substitute LT-059K-1-R
3.5 coils, 1.6 fi wire
f-
“‘Lee Spring Company, 30 Mail; St., Brookly;, >A! 11201:
zd,alog Xo. 112/1970
Scale: .87 : 1
Trigger
Material: AISI 1 0 1 0 or equivalent,,
1.6mm stock
Heat treat: none
Scale: .8 7 : 1
3.8 I; I ’
71.
) 16.6
Trigger assembly
Top view
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1
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-
Sear pin
Sear lever 7
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‘l’rlgger s p r i n g 1 1 1
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----mm
Bottom view
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/
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1
/
Sear
Material: AISI 4140 or equivalent
Harden to Rc 55
Scale: 1 : 1
L 3.1 $ driil rod
Y- 2.8R
2.8
i
Magazine
Material: lmm steel stock
--I_
.
87
--r
Top view
Rear view
Front view
3.2R
f
Bottom view
Magazine follower
Material: low carbon steel
Scale: 1 : 1
3.6R
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(ciearance for magazine body)
we--__
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60.5
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34.8 ref.
Note:
-+I
The *magazine follower is a compks stamping made on
a progressive die. To make a follower in a simpler way
is to follow the Degtyarev DP LAIG approach - using
a dummy round as the last one in the magazine. Thus a
simple, flat follower with a dummy round soldered
and/or screwed to it will replace a complicated stamping.
0
’:
w.
4
VIagazine spring
Material: Music wire 1.5mm dia.
6.5R ref.
- \
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-,-_I
/
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I- -
r-
Over-all length: 313
Number of.coils: 26
-
27.7 -
/ r 6.5R
S c a l e : .87 : 1
Magazine bottom retainer
Material :
lmm mild steel
P - - - - 3 1 ---I
5
L 6 .5 R
3 1
I
Retaining lip bent over magazine
spring tab at assembly
Magazine bottom plate
Material: lmm mild steel
r
3
Sale: -87 : 1
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