M3A1 "Grease Gun" Submachine Gun

Take a close look at the M3A1 “Grease Gun” — the compact, rugged .45-caliber submachine gun that was designed for cheap, rapid wartime manufacture and service in World War II and beyond. Chambered in .45 ACP and firing from an open bolt, the M3 family was introduced during WWII as a lighter, low-cost alternative to the Thompson.

In this video we examine the M3A1’s key features: simple stamped-steel construction, the recessed cocking slot (which replaced the crank cocking lever), the 30-round box magazine, and the design choices that kept production fast and inexpensive.

You’ll also hear about the M3A1’s service history — how it entered service in the mid-1940s, saw use in Korea and later conflicts, and continued to serve in secondary roles long after frontline replacement.