The M3 Grease Gun was designed as a cheap, mass-produced replacement for the Thompson, costing $15 to produce vs $70 for the Thompson. Issued to tank crews and paratroopers who needed a compact automatic weapon. Used from WWII through Desert Storm. Type: Submachine Gun Action: Blowback Caliber: 45 ACP Capacity: 30 Year introduced: 1942, USA Weight: 8.15 oz Overall length: 22.8" Status: Discontinued Military use: Yes Intended use: Military, Collector, Historical