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Expedient Homemade FirearmsExpedient Homemade Firearms:The 9mm Machine PistolBy P.A. Luty(D.F.C)Copyright C.2004 by P. A. Luty.A Home Gunsmith PublicationAll rights reserved. Anyone attempting toreproduce any part of this publication in any formwithout the express written permission of theauthor will be tried, sentenced and shot, (and notnecessarily in that order)Direct all enquiries/orders to:www.thehomegunsmith.comNeither the author nor publisher assumes anyresponsibility for the use or misuse of the informationcontained in this book.-2-

Expedient Homemade FirearmsIntroductionReaders of ‘Expedient Homemade Firearms’ Volume Iand II may find the following 9mm Machine Pistol designof interest.The firearm is constructed using similar materials andtechniques as those illustrated in my previous books.The following construction drawings will be familiar toreaders already conversant with my previous designs.The pistol uses the same design magazine shown inVolume I, though I have included the magazine baseplate spring design, shown in Volume II, as a designimprovement.I have designed the bolt to be a simple unit easilymachined using a lathe, rather than assembling the boltfrom the selection of hardware products shown inVolume I and II.In short, I have designed the machine pistol with theslightly more advanced home-gunsmith in mind and toenable relatively simple home workshop construction.-3-

-4-Expedient Homemade Firearms1. RECOIL SHIELD BOLT2. GUIDE WASHER3. MAINSPRING4. BOLT5. BOLT HANDLE6. EJECTOR7. SLING LOOPS8. BARREL RETAINER SCREW9. BARREL10. BARREL COLLAR11. MAGAZINE WELL12. MAGAZINE13. BASE PLATE SPRING14. MAGAZINE CATCH15. RETAINER SCREW16. TRIGGER17. SEAR18. SEAR/TRIGGER SPRING19. RETAINER SCREW20. GUIDE RING21. GUIDE COLLAR22. RECOIL SHIELD

Expedient Homemade FirearmsMATERIALS REQUIREDTUBINGUpper Receiver40 x 40 x 2.5mmLower Receiver25.40 x 25.40 x 2.5mmMagazine Well40 x 20 x 2mmMagazine34.93 x 15.88mmTrigger Group Receiver20 x 20 x 2mmBarrel15.00 x 3.00mmSPRING STEELMagazine Catch7/16” x 18 Gauge Spring SteelMainspring20 Gauge Spring WireFLAT BARTrigger Guard5/8 x 1/8” Flat BarTOOL STEELSear3/8” PlateTrigger¼” PlateROUND BARBolt35mm Dia’.Note: Measurements are supplied in either Metric or Imperial sizes in accordance with themeasurements materials are usually encountered.-5-

Expedient Homemade FirearmsTEMPLATESGRIPINSERT35 X16mmTUBEMAGAZINEWELL40 x 20mmTUBEGRIP40 X 20mmTUBESEAR3/8”TOOL STEELMAGAZINECATCH7/16” x 20gSPRING STEELTRIGGERGUARD5/8 x 1/8”FLAT BARTRIGGER¼” PLATE-6-

Expedient Homemade FirearmsTEMPLATESLOWER RECEIVERTOP169mmCUT OUT AND REMOVE SHADED AREAS.HOLE POSITIONS.SIDEThe overall length of the template is 169mm.If the template is not 169mm in length when printed, it can be enlarged asnecessary using a photocopier, until the above measurement is achieved.-7-

Expedient Homemade FirearmsTEMPLATESTRIGGER GROUP RECEIVER(Hole diameters not to scale)TOP128mmCUT OUT AND REMOVE SHADED AREAS.SIDEBOTTOM-8-

Expedient Homemade FirearmsMAGAZINE TEMPLATE34.93 x 15.88 x 1.6mm Tube.Cut Slot 1– 1.5mmdeep toacceptbase platespringretainer.9 -1/8”REAR TEMPLATESee ‘Volume One’ for mainspringand follower construction.SIDETEMPLATEDrill Hole: 1 – 1.5mm.-9-

Upper Receiver Recess Positions.16 ¼” length of 40 x 40 x 2.5mm tubing(All measurements in millimeters)- 10 Expedient Homemade Firearms

Expedient Homemade FirearmsLOWER RECEIVERCONSTRUCTION.The two templates are glued to a length of 1” x 1” x 12g tubing, as illustrated below.After cutting out, the receiver should look like the illustrated below.4mm HoleCompletely cut out and remove bottom sidewall of receiver.- 11 -

ASSEMBLING THE UPPER ANDLOWER RECEIVERSUPPER RECEIVERINSERT RECEIVER11mm- 12 -LOWER RECEIVERThe magazine well is held in placeby silver soldering at points ‘a’ and‘b’ or welding at points ‘c’ and ‘b’.Ensure top corner ofmagazine well protrudes11mm above top of receiver.Expedient Homemade FirearmsMAGAZINEWELL

THE UPPER AND LOWERRECEIVER ASSEMBLY- 13 Expedient Homemade FirearmsThe two receivers are welded together at points ‘a’ ‘b’ and ‘c’.

Expedient Homemade FirearmsTRIGGER GROUP RECEIVERCONSTRUCTION.The two templates are glued to a length of 20 x 20 x 2mm tube.Hole diameters: a) 6mm, b) 7.8mm, c) 7.8mm, d) 3.8mm.(Hole diameters not to scale)After cutting out, the receiver should look like the one illustrated below.- 14 -

Expedient Homemade FirearmsTRIGGER MECHANISMThe trigger mechanism consists of the sear, sear spring, trigger and magazine catch.The trigger group receiver is now ready to be fitted with all the above parts.See ‘Templates’.SearThe sear is cut and shaped from a section of 3/8” (9.5mm) steel plate (tool steel/gaugeplate, etc*) The sear pivot pin hole is drilled to a diameter of 8mm and accepts an 8mmdiameter dowel pin, (Figure 4, Page 32) or similar hardened steel pin.TriggerThe trigger is shaped from a ¼” (6.35mm) thick section of tool steel/gauge plate, etc.The trigger pivot pin hole is drilled to a diameter of 4mm to accept a 4mm diameter dowelpin, or similar (Figure 10). The second trigger hole is drilled to a diameter of 2mm andaccepts a pin of 2mm diameter (Figure 11). A spring pin may be used for this purpose. Thetrigger should then be polished to a smooth finish.Magazine catchThe magazine catch (Figure 7) is formed to the correct shape by bending a length of 7/16”spring steel strip material to the shape of the magazine catch template. The catch should bemade from 18 or 20 gauge spring steel using the same simple methods described earlier inExpedient Homemade Firearms Volume II. The spring is bolted to the front section of thetrigger guard (Figure 6). The hole in the front of the guard may be tapped to accept a 4mmdiameter socket screw, or the catch can be secured with a simple nut and bolt arrangement.Sear and Trigger SpringThe sear and trigger spring is formed by bending a length of 20 gauge spring wire aroundan 8mm diameter mandrel (steel rod). The shape and design of the spring will be selfexplanatory from the drawing (Figure 1). When the trigger, sear, and sear spring are fitted, itshould be noted that the dowel pins must not protrude beyond the outer surface of thereceiver wall.The parts must be fitted in the correct order, i.e., the trigger first, followed by the spring andsear. Finally, ensure all parts are moving freely and make any necessary adjustments.Note*. ‘Gauge Plate’ is readily available from any good model engineering store and fromsome tool shops and ironmongers, etc. Each length of plate is sold with its own hardeningand tempering instructions and the hardening process can be easily carried out with anordinary propane gas torch. Although not an ‘ideal’ steel for the purpose, its readyavailability makes it an obvious choice for trigger and sear construction in the improvisedfirearm.Note: The sear and trigger could be made quiet easily from a piece of mild steel, and casehardened using ‘Kasenit’ case hardening powder as a cheaper alternative to tool steel.- 15 -

Expedient Homemade FirearmsTRIGGER GROUP COMPONENTSCOMPONENTS1. TRIGGER/ SEAR SPRING2. DOWEL PIN3. SEAR4. DOWEL PIN5. RECEIVER6. MAGAZINE CATCH SCREW7. MAGAZINE CATCH8. TRIGGER GUARD9. TRIGGER10. DOWEL PIN11. DOWEL PIN12. GRIP13. GRIP INSERT- 16 -

Expedient Homemade FirearmsASSEMBLING THE RECEIVERINSERTGUARDINSERTGRIPCUT SLOTDrill 4mm diametermagazine catch hole.Silver solder points ‘a’ ‘b’ and ‘c’.- 17 -

Expedient Homemade FirearmsTRIGGER GROUPAND GRIP ASSEMBLYThe trigger group assemblycan now be fitted to the lowerreceiver.- 18 -

FITTING THE TRIGGER GROUP RECEIVERBA.- 19 -A. 6mmB. 4mmThe magazine is now constructed and fitted.Expedient Homemade FirearmsThe trigger group receiver is now fittedto the lower receiver and is held in placewith socket screws ‘a’ and ‘b’.Position ‘a’ is drilled and tapped toaccept the screw. Position ‘b’ is drilledall the way through the receiver toaccept a screw and nut.

Expedient Homemade FirearmsMAGAZINE CONSTRUCTION(The magazine is made from a length of 34.93 x 15.88mm 16g tubing, using the sametechniques shown in ‘Expedient Homemade Firearms’, Volume One)FORM BLOCKThe form block is made from a length of 1” x ½” flat steel bar.MAGAZINE LIPSThe magazine lips should be set 9mm apart.MAGAZINE SPRINGThe magazine spring is coiled using 20 gauge spring wire.MANDRELThe magazine spring mandrel is made from three 14” lengths of8mm diameter steel rod, brazed/silver soldered together.FOLLOWERThe follower is formed from a length of steel sheet, 2 ½” inlength and ½” in width.BASE PLATE SPRINGThe base plate spring is formed from 20 gauge spring wire.- 20 -

BARREL CONSTRUCTION(All measurements in millimeters)2735A1315 x 3mm Hydraulic Tube.B35- 21 Expedient Homemade FirearmsThe barrel overall length is 6 ½”.The two collars are machined to the abovedimensions and inserted onto the barrelsbreech and muzzle.Collar ‘A’ is retained with bearing adhesive.Collar ‘B’ is silver soldered in place.

Expedient Homemade FirearmsRECOIL SHIELD DIMENSIONS.(Measurements in millimeters)The recoil shield is machined to the following dimensions.388.5mmHole.351813Cut away view.GUIDE RODThe measurement between washer and tip of guide rod should be 88mm.b.d.c.88mma.A: 6mm Shaft Lock Collar.B: Washer.C: Steel Ring (Tube section-8mmOD max) Solder in place.D: 6mm (or ¼”) Rod.- 22 -

Expedient Homemade FirearmsCUT AWAY VIEW OF RECOIL SHIELDAND GUIDE ASSEMBLYCut away view.Recoil Shield Bolt Hole.The recoil shield bolt hole should be tapped to accept two 10mmdiameter high tensile socket screws. The two socket screws retain therecoil shield within the upper receiver.MAINSPRINGThe mainspring is coiled around a 5.5mm (7/32”) mandrel to a length of14” using 20 gauge spring wire. Following ‘compression shrinkage’, trimthe spring to a length of 10”. See ‘Expedient Homemade Firearms’Volume One, for full spring coiling techniques.- 23 -

Expedient Homemade FirearmsBOLT CONSTRUCTIONAs illustrated in ‘Expedient Homemade Firearms’ Volume Two, the boltfor the 9mm machine pistol must be machined from a suitable steel.Machining the bolt is a relatively simple turning procedure. Start with asection of round bar, 35mm in diameter and machine the bolt to thefollowing dimensions.Bolt outside diameter (A1) is 35mm and the bolts overall length (OAL) is127mm. Machine the front section (A2) to an OAL of 48mm and a diameter of14mm (A3).Mainspring/guide recess (B1). Using a 5.5mm drill bit, the recess B1 ismachined to a depth of 93mm. Using a 9mm diameter drill bit the recess is rebored to a depth of 74mm.Cartridge recess: The cartridge recess (B2) is 10mm in diameter and 2.5mmin depth.Ejector slot (C1) is cut to a depth of 3.5mm. The slot is 30mm in length andhas a width of 3mm (C2). The slot may be cut by drilling a series of holes toremove most of the steel before trimming the slot to its correct dimensions.Firing pin (D1) dowel pin/drill shank, etc, is 2mm in diameter and seated to adepth of 12mm. The pin must protrude from the face of the cartridge recess by1.5mm (D2).Bolt handle hole (E1) is machined 18mm from the front face of the bolt and istapped to accept an 8mm diameter socket screw. The bolt handle hole isdrilled to a depth of 10mm and must not cut through into the mainspringrecess.Note: The ejector slot is the final recess to cut. Before the slot can be made itscorrect position on the bolt radius must be marked. To do this simply insert thebolt into the receiver and screw in the bolt handle. Insert a pointed implement,nail/scribe etc, through the ejector hole and scribe the position of the slot ontothe bolt by simply drawing the bolt back and forth. Cut the slot at this positionto the dimensions given at C 1 and C 2.- 24 -

Expedient Homemade FirearmsBOLT DIMENSIONS(All measurements in millimeters)- 25 -

Expedient Homemade FirearmsBOLT HANDLE POSITION.E.118mmThe bolt handle hole is drilled 18mm from the front face of the bolt.The Finished Bolt.- 26 -

THE RECOIL SHIELD, GUIDE ROD, BOLT AND BARRELSHOWN IN THEIR RESPECTIVE POSITIONS.- 27 GUIDEBOLTBARRELExpedient Homemade FirearmsSHIELD

Expedient Homemade FirearmsTHE MACHINE PISTOL’S MAJORCOMPONENT PARTS.- 28 -