M3 (Grease Gun) (ID 9.18)

The M3 is an American .45 caliber submachine gun adopted by the US Army on 12 December 1942, as the United States Submachine Gun, Cal. .45, M3. The M3 was chambered for the same .45 ACP round fired by the Thompson submachine gun, but was cheaper to mass produce and lighter, although, contrary to popular belief, it was less accurate. The M3 was commonly referred to as the "Grease Gun" or simply "the Greaser," owing to its visual similarity to the mechanics tool.

The M3 was intended as a replacement for the Thompson, and began to enter frontline service in mid-1944. The M3A1 variant was used in the Korean War and later conflicts.