Blueprints
A widely circulated 24-page anonymous dimensioned drawing set for the Mk II: parts list, then per-part drawings of the receiver, bolt, barrel, trigger mechanism and furniture. Not an official MoS drawing set; verify any critical dimension against the official documents before cutting metal.
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. Please set up Acrobat to “View - Bookmarks and Page” Sten Mk II PARTS LIST 1. 2. 3 Barre I Barrel sleeve Barre I sleeve lock Barre 1 sleeve lock spring l 4. Front sight 5. 6. 7. 8. Barrel bushing Receiver tube Receiver cap Trigger housing 9 lb. Butt stock assembly: : i 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 11. Magazine housing 12. Magazine housing spacer 13. Magazine housing spacer screw 14. Magazine latch 15. Magazine latch spring 16. Trigger 17. Trigger spring 18. Trigger pin 19. Disconnector 20. Disconnector pin 21. Selector 22. Selector spring 23. Selector plunger (2) 24. Sear 25. Sear syring 33. Closing spring 34. Closing spring cup 35. Trigger housing cover 36. TrigF: housing cover screw (2) 37. Magazine houskg 38. Magazine follower 39. Magazine spring 40. Magazine spring latch 41. Magazine botiom 42. Rear sight NOTES: 1 . Bolt stopping surface on barrel is lmm f o r 2. ward of magazine well slot. Bolt stroke is 135mm. I I’ I_ I \ --- /+ /--/ , ,>’ / f- m - - _ i- - 0 I 6 Receiver tube Material: seamless steel tubing I f- _-_- _ -__~ cc? / _A_:i -_-- / q$ 1 1 / dd;L <. \ 1.5R typ. (\ -I- --me---s--B I’ I 1 Main spring cap Material: Imm stock -e-v-- I _ I_. ._ -- ----_( .__ 1 !s - c_ - I --a--_ Scale: 1 : 1 I I I 1 ------__- 151‘ I k--- 45 Receiver rear end b u s h i n g Material: AISI 1010 or equivalent Scale: 1 : 1 \ r r-1 I - I ’I I 1 I 20R 1f J_ 2.5 ! Barrel hushing Material: 4140 Scale: Barrel sleeve I 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 ‘* I 70 13 - -I II 1 I i I 7 -5 - I * 5 7- I fT” 1’ I 1 1 I -y 44 ! I I II 4 1 1 i ’ I- i ’I 14.5 t 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 I I-- 0 &5R 1 \ 4 1 . 5 , I Bolt handle S c a l e : 37 : 1 Material : mild steel Heat treat: none 59. 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 I -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 Extension spring LE-026B-7 or loops LE-026C-8 Selector 0.45 4 .6 14 Gr . Barrel sleeve latch 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 1010 or equivalent,, 1.6mm stock Heat treat: none Scale: .8 7 : 1 3.8 I; I ’ 71. ) 16.6 Trigger assembly Top view I--- - -1-r Ir----i= I ’ I 1 1; ” 1 ’ I ’ L L i 1 m-- m =L L -Y---- - Sear pin Sear lever 7 / \\ J \ \ \ / \ \ 4 \ \ -’ \ -lr--. \ I ‘l’rlgger s p r i n g 1 1 1 I I I ’ I ’ \\ -- - \ ).i m- ----mm Bottom view ’ I I I I / I 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 I I \’ I -_--__ I I I I I (ciearance for magazine body) we--__ i I 60.5 I I I I I .I I I I I I I I- 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. - \ I- I -,-_I / I - 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 r3 Sale: -87 : 1 I I I f L 1