The final wartime revision of the Thompson Submachine Gun, the M1A1 replaced the articulated firing pin in the bolt with a fixed pin on the bolt face, which by that point had become the de-facto standard for SMG bolt design. The barrel is an earlier "AC" pattern, with a blade sight on the "Thompson" marked Cutts compensator and the signature cooling fins, and the rear sight a one-piece fixed peep sight with integral protective wings marked "J". The receiver is marked "U.S./PROPERTY" on top, with the 3-line model and S/N markings on the left side, 2-line address on the right, and faint "GEG" and "FJA" inspector marks near the breech. The blued trigger housing is numbered "644642. Fitted with a grooved horizontal forearm, pistol grip, and a fixed buttstock with a smooth steel buttplate. Included with the lot is a soft case and eleven extra stick magazines (chiefly Seymore Products production).