Submachine Guns Caliber .45 M3 and M3A1: FM 23-41

The M3 was an American .45-caliber submachine gun adopted for U.S. Army service in December of 1942, as the United States Submachine Gun, Cal. .45, M3. Compared to the Thompson submachine gun, the M3 was cheaper to produce, lighter, and more accurate. The M3 was commonly referred to as the "Grease Gun" or simply "the Greaser," due to its visual similarity to the mechanic's tool.Intended as a replacement for the .45-caliber Thompson submachine gun, the M3 began to replace the Thompson in fir...