M3 submachine gun, right side view.
M3 submachine gun is full-automatic only, blowback operated firearm that fired from open bolt. The receiver is made from steel stampings. M3 featured spring-loaded ejection port cover (which also also act as safety,locking the bolt when it is closed) and crank-type bolt retracting (cocking) handle at the right side of the receiver. In M3A1 the designers removed cocking handle assembly (which was source of malfunctions) and replaced it with simple finger hole in the bolt body, accessible through enlarged ejection window. Also, M3A1's could be converted for 9x19mm Luger ammunition by replacing the barrel, bolt, and installing the magazine adaptor to use British STEN magazines.
M3 submachine gun, left side view, shoulder stock fully retracted.
The retractable stock, made from steel wire, could be used as cleaning rod (when detached),and it also featured a magazine loading tool. The hollow grip of the gun contained a small oilier, which was necessary as the all-steel gun rusted easily in wet climate.
M3 submachine gun, partially disassembled. Note dual return springs and a separate cocking mechanism housing.
A special version of the M3A1 was produced for clandestine operations; it featured long, integral silencer.
M3A1 submachine gun. Note enlarged dust cover, absence of a cocking handle and optional flash hider.
Rare version of M3A1 submachine gun, fitted with integral silencer.