Bolt Construction

As illustrated in 'Expedient Homemade Firearms' Volume Two, the bolt for the 9mm machine pistol must be machined from a suitable steel.

Machining the bolt is a relatively simple turning procedure. Start with a section of round bar, 35mm in diameter and machine the bolt to the following dimensions.

Bolt outside diameter (A1) is 35mm and the bolts overall length (OAL) is 127mm. Machine the front section (A2) to an OAL of 48mm and a diameter of 14mm (A3).

Mainspring/guide recess (B1). Using a 5.5mm drill bit, the recess B1 is machined to a depth of 93mm. Using a 9mm diameter drill bit the recess is re-bored to a depth of 74mm.

Cartridge recess: The cartridge recess (B2) is 10mm in diameter and 2.5mm in depth.

Ejector slot (C1) is cut to a depth of 3.5mm. The slot is 30mm in length and has a width of 3mm (C2). The slot may be cut by drilling a series of holes to remove 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 a depth of 12mm. The pin must protrude from the face of the cartridge recess by 1.5mm (D2).

Bolt handle hole (E1) is machined 18mm from the front face of the bolt and is tapped to accept an 8mm diameter socket screw. The bolt handle hole is drilled to a depth of 10mm and must not cut through into the mainspring recess.

Note: The ejector slot is the final recess to cut. Before the slot can be made its correct position on the bolt radius must be marked. To do this simply insert the bolt 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 onto the bolt by simply drawing the bolt back and forth. Cut the slot at this position to the dimensions given at C 1 and C 2.

Machine Pistol Bolt

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