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).

Very fine as assembled and refinished. The receiver shows 97% plus reparkerization, with some areas of covered-over pitting and mild handling marks and spotting overall. The barrel shows a strong high-polish blue with a loose Cutts compensator, and the trigger housing retains most of the finish, with spotting on much of the surface, edge wear, and a number of scuffs and tool marks on the right side. The furniture is good as cleaned/sanded, with mild handling marks. Mechanically excellent. NOTE: This weapon is a National Firearms Act (NFA), fully transferable Class 3, which is registered with the Bureau of Alcohol, Tobacco, Firearms and Explosives, (BATFE) that is classified as a "Curios or Relic" as defined in 27 CFR, 478.11. These weapons are still subject to the provisions of 18 U.S.C. Chapter 44 and 27 CFR part 478.