M3 / M3A1 "Grease gun"
M3. Note bolt retraction handle behind the magazine veil
M3A1. Ejection port cover opened
M3A1. another view
M3A1. stock retracted.
The M3 submachine gun, also known as Grease gun, was developed as a cheaper war-time alternative to famous Thompson M1 and M1928 submachineguns. M3 and M3A1 were developed and manufactured by General Motors Corp. M3 was introduced in 1942, and simplified M3A1 was introduced in 1944, and remained in service (in the USA) until 1960 or so, and also was exported.
M3 is full-auto only, blowback operated firearm. The receiver is made from steel stampings. M3 featured spring-loaded ejection port cover (also acted as safety) and crank-type bolt retracting (cocking) handle at the right side of the receiver. In M3A1 the designers removed cocking handle assembly (it was prone to malfunctions) and replaced it with simple finger hole in the bolt body, accessible through enlarged ejection window. Also, M3A1's were able to be converted to use 9mm Luger rounds by replacing the barrel, bolt, and installing the magazine adaptor to use british Sten magazines. Both M3 and M3A1 fired from the open bolt.
The retractable stock, made from steel wire, could be used as cleaning rod (when detached), it also featured a magazine loading tool. Some M3s and M3A1a were also fitted with flash hiders. The sights were fixed and were located at the top of the receiver.
.45ACP (also 9x19mm Luger/Para in M3A1)
(stock closed/open): 570 / 745 mm
Rate of fire: