Sear Construction

The sear is cut from a section of 1 8 thick steel plate. See templates, page 3. A 4mm diameter dowel pin is tapped into the sears 3.8mm hole. The pin should protrude 8mm from the sears right side when fitted. The sear is made from mild steel and should be case hardened after final shaping.

Fully Assembled Lower Receiver

We can now begin construction of the upper receiver The upper receiver assembly consists of a BSP tube screwed at both ends and fitted with a Cap and Reducer, as photo 'A' below illustrates. Photo 'B' shows the reducer and cap screwed onto the receiver tube and the barrel assembly ready for fitting. The upper receiver template must be enlarged using a photocopier until it is 12 Y2 in length. Once enlarged, the template is glued around the 1 W BSP upper receiver tube. The recesses for the...

Bolt Assembly

Smg Bolt Assembly

The bolt is machined to the following dimensions from a suitable section of round steel stock. The buffer is made from a section of hard rubber stock to the following dimensions. The spring guide is nothing more than a length of 1 diameter tubing. The tubing should have a wall thickness of 1 8. An alternative to machining the SMG bolt would be to assemble it from the components illustrated below. The components are fitted to the 8mm bolt section as shown below. The Y2 spring pin is two inches...

Lower Receiver Assembly

Lower Reciever Gap

To create the lower receiver assembly, the two receiver side- plates are joined together by spacing them between two 6mm studding connectors, A and B . Four dome head cap screws are then screwed into the connectors and thoroughly tightened, effectively holding the assembly together. The two connectors must be exactly 20mm in length. As bought, 6mm connectors are usually this exact length, but if they are not, they may be trimmed on a lathe until the required length is achieved. A section of...

Fitting The Mainspring

Bsp Smg Full Auto

After placing the bolt into the upper receiver, the mainspring can be inserted, followed by screwing on the BSP cap. See final page, ''Construction Notes'' for tips on acquiring mainspring . Drill two 2mm diameter holes through the Magazine body and cap to retain the cap in position. A 34.93 x 15.88mm plastic tube cap is used to seal off the bottom of the magazine. As shown in Expedient Homemade Firearms -The 9mm Sub-Machine Gun, the magazine is made from a section of 34.93 x 15.88mm...


Improvised Firearm

The weapon shown in the following document has not been built and is therefore a prototype design only. All photo's illustrate plumbing hardware components shown in their unmodified as bought condition. The following design drawings illustrate the construction of a 9mm submachine gun utilizing off the shelf 'British Standard Pipe' BSP Fittings. BSP fittings, commonly known as 'Malleable Iron Fittings', are readily available from most good trade plumbing outlets. Because this BSP machine gun...

Lower Receiver Template

Hole diameters shown in millimetres The lower receiver is composed of two receiver side- plates, each being 9 '' in length. Each plate is identical. Each side - plate is cut from a length of 2.5mm thick steel sheet to the shape of the above template. The square recess shown in figure 'A' is the anchor point for the shoulder stock. This measures '' square. Note If the template is not 9 '' in length when printed, it may be enlarged using a photocopier until the necessary length is achieved.


9mm Bsp Machine Gun

Pin must protrude 6mm from each side of trigger. The trigger is made from a section of W thick steel plate. A 4mm diameter dowel pin a spring pin could be used as a substitute is tapped into the 3.8mm hole. The pin must protrude 6mm from each side of the trigger when fitted. Before the sear is fitted, a slot is cut through the rear and front of the grip wall. The slot is 15mm deep and 4mm wide. The sear is inserted into this slot and retained with a 6mm diameter dowel pin. This pin should be...

Assembling The Barrel

Bsp Smg Pictures

The BSP nipple, socket, and lock nut assembly are screwed into the reducer. The assembly is then thoroughly tightened. The barrel tube is inserted into the BSP barrel assembly. The barrel tube is inserted into the BSP barrel assembly. The barrel is assembled from a 9 length of 15.88 x 3.25mm hydraulic tubing, a 1 BSP Reducer, 1 2 BSP Lock nut, 1 2 BSP Socket, and a 1 BSP Nipple threaded tube . Screwing the barrel assembly onto the upper receiver. Screwing the barrel assembly onto the upper...