Expedient Homemade firearms Prototype Design Drawings T T H H E E ‘ ‘ Z Z I I P P ’ ’ G G U U N N (Measurements in millimetres unless otherwise stated) T T h h e e Z Z i i p p , , o o r r P P e e n n G G u u n n , , a a s s i i t t i i s s s s o o m m e e t t i i m m e e s s r r e e f f e e r r r r e e d d t t o o , , i i s s p p e e r r h h a a p p s s t t h h e e s s i i m m p p l l e e s s t t o o f f a a l l l l i i m m p p r r o o v v i i s s e e d d f f i i r r e e a a r r m m s s a a n n d d i i s s u u s s u u a a l l l l y y f f o o u u n n d d i i n n . . 2 2 2 2 c c a a l l i i b b r r e e d d u u e e t t o o t t h h e e r r e e l l a a t t i i v v e e l l y y l l o o w w p p r r e e s s s s u u r r e e s s g g e e n n e e r r a a t t e e d d b b y y t t h h i i s s s s m m a a l l l l c c a a r r t t r r i i d d g g e e . . I I d d e e c c i i d d e e d d t t h h a a t t a a n n e e e e d d e e x x i i s s t t e e d d f f o o r r a a s s i i m m p p l l e e h h o o m m e e m m a a d d e e v v e e r r s s i i o o n n o o f f t t h h i i s s t t r r i i e e d d a a n n d d t t e e s s t t e e d d ‘ ‘ ’ ’ c c o o n n t t r r a a p p t t i i o o n n ’ ’ ’ ’ a a n n d d c c a a m m e e u u p p w w i i t t h h t t h h e e f f o o l l l l o o w w i i n n g g d d e e s s i i g g n n ! ! I I d d e e s s i i g g n n e e d d t t h h i i s s w w e e a a p p o o n n w w i i t t h h t t h h e e c c a a v v e e a a t t t t h h a a t t i i t t s s h h o o u u l l d d b b e e b b u u i i l l d d a a b b l l e e i i n n o o n n e e d d a a y y o o r r l l e e s s s s , , a a n n d d I I t t h h i i n n k k I I h h a a v v e e a a c c h h i i e e v v e e d d t t h h a a t t r r e e q q u u i i r r e e m m e e n n t t . . T T h h e e R R e e c c e e i i v v e e r r . . The receiver is basically a steel tube into which the other component parts are fitted. It consists of a 9 ¼ “ (233mm) length of 15.88mm (5/8”) x 1.5mm steel tubing, as illustrated below. Into this tube a slot is cut, either by drilling a series of interconnecting holes first, and then trimming the slot to shape with a file, or (for the lucky individual) cut using a milling machine, if available! The slot should be ¼” in width and will accept the breech block handle in due course. The slot is 98mm in length, starting 67mm from any end of the tube. C C o o m m p p o o n n e e n n t t P P a a r r t t s s ( ( T T h h e e r r e e a a r r e e o o n n l l y y t t h h r r e e e e c c o o m m p p o o n n e e n n t t p p a a r r t t s s t t o o t t h h e e w w e e a a p p o o n n ) ) 1. Barrel 2. Breech Block 3. Breech Plug 4. Mainspring 67 98 Small Cut out in rear of slot to allow the weapon to be cocked. Expedient Homemade firearms Prototype Design Drawings B B a a r r r r e e l l C C o o n n s s t t r r u u c c t t i i o o n n . . The Barrel can be nothing more than a short length of steel Airgun barrel, turned to a diameter of 12.70mm (½”). The length of the barrel is 75mm. One end of the barrel is chambered using a 5.8mm diameter drill bit to accept the .22 rimfire cartridge. B B r r e e e e c c h h B B l l o o c c k k The breech block is just a 58mm long section of ½” diameter mild steel bar. Into one end of the block a firing pin is fitted, made from a short length of 2mm diameter drill shank. The pin must be carefully fitted so as to be in the correct position to detonate the .22 rimfire cartridge. 75mm 58mm Near to one end of the breech block a ¼” Dia’ hole is drilled to accept the breech block cocking handle. The handle consists of a simple steel pin about 1” in length. FIRING PIN BARREL Breech Block Expedient Homemade firearms Prototype Design Drawings M M a a i i n n s s p p r r i i n n g g The mainspring powers the breech block and should be reasonably strong. I designed this gun to use a spring about 8- 9mm in diameter and made from 20 gauge wire. T T h h e e B B r r e e a a c c h h P P l l u u g g The breech plug is responsible for holding the spring and breech block in place. It consists of nothing more than a 1” x ½” spring pin. The pin is held in place by a 6mm diameter steel bolt and nut which passes through the receiver from side to side, as illustrated below. F F u u l l l l y y A A s s s s e e m m b b l l e e d d Pull back cocking handle and turn to right to cock weapon. Load cartridge. When ready to fire disengage handle using thumb or finger…… Bang! Pull Back Handle Bolt This design may be very simple, but I think it would be easy and quick to build ! Breech Plug (Spring pin retained with nut and bolt) Breech Block Barrel Expedient Homemade firearms Prototype Design Drawings A A f f e e w w e e x x a a m m p p l l e e s s o o f f Z Z i i p p / / P P e e n n g g u u n n s s b b u u i i l l t t b b y y o o t t h h e e r r p p r r i i v v a a t t e e i i n n d d i i v v i i d d u u a a l l s s a a n n d d a a r r m m s s m m a a n n u u f f a a c c t t u u r r e e r r s s . . Armitage Pen Gun. www.lawdogs.8m.com/ catalog.html ‘’Stinger’’ Pen Gun. www.gurpsmaster.de/ undercover.htm ‘‘Mini Mag Light’’ .22 Torch Guns. www.lawdogs.8m.com/ catalog.html Expedient Homemade firearms Prototype Design Drawings American factory made ‘’Pen’’ pistol. www.gurpsmaster.de/ undercover.htm Unknown origin. Very nice homemade Pen Gun. http://membres.lycos.fr/abpw/22-misc/pages/Pen_Gun1_by_Nobody.htm Expedient Homemade firearms Prototype Design Drawings A .44 calibre Pen Gun. This is an old collectors piece made by the ‘Lake Erie Chemical Co’. www.adrax.com/ watsons/pengun.htm . http://membres.lycos.fr/abpw/22-misc/pages/Pen _Gun1 _by_Nobody.htm Expedient Homemade firearms Prototype Design Drawings A .44 calibre Pen Gun. This is an old collectors piece made by the ‘Lake. slot to allow the weapon to be cocked. Expedient Homemade firearms Prototype Design Drawings B B a a r r r r e e l l C C o o n n s s t t r r u u c c t t i i o o n n . . The Barrel. length of steel Airgun barrel, turned to a diameter of 12.70mm (½”). The length of the barrel is 75mm. One end of the barrel is chambered using a 5.8mm diameter drill bit to accept the .22 rimfire