The final wartime revision of the Thompson Submachine Gun, the M1A1 was on paper made obsolete by the M3/M3A1, but would continue to serve as late as the Vietnam War. Blade front and fixed peep rear sights, with a horizontal handguard, and an "A.O.C." marked machined receiver with "GHD" stamp. The mixed numbered trigger housing has dual control switches, a fixed buttstock, and a grooved pistol grip. Bolt is M1A1 pattern, with a fixed firing pin on the bolt face and no provision for a Blish lock or oiler. Magazine and buffer assembly absent.