The Auto-Ordnance, Bridgeport plant was under the jurisdiction of the Springfield Ordnance District in 1941. Most of the Auto-Ordnance, Bridgeport Thompsons were fitted with the late (4th) style compensator that has the Thompson bullet logo on the left side, and the Auto-Ordnance name roll marked across the top of the leading edge.Īll M1928A1 model Thompsons made at the Auto-Ordnance, Bridgeport plant were originally fitted with the horizontal style foregrips. The Cutts compensator was retained on all military A-O 1928A1 models throughout production.
Thus, a low numbered Auto-Ordnance 1928 model was manufactured at the same time period a mid-range number Savage gun. The reason is that the Savage factory began manufacturing the guns approximately eighteen months before Auto-Ordnance. Note while the L sight and smooth barrel began to appear on mid-range serial number Savage 1928s they appeared on lower numbered Auto-Ordnance, Bridgeport guns. In early production the finned barrel was still fitted on the Auto-Ordnance, Bridgeport guns, but was eventually replaced by the easier to manufacture, smooth barrel that began to appear at the 85,000 serial number range.Īs with the rear sights there was no defining line on the type of barrel that was installed on any particular serial number range on Auto-Ordnance Thompsons.Įven after the smooth barrels began to be fitted, the finned style barrels continued to sporadically appear through the entire serial number range until the end of production. However, there was no defining line where the use of the Lyman adjustable sight was discontinued, as they continued to appear sporadically throughout the entire range of serial numbers. The parts that were manufactured in house by Auto-Ordnance were stamped with the letters AO or AOC.Īs production continued the Auto-Ordnance Thompsons, like the Savage manufactured guns, also began to be fitted with the simple stamped fixed L style aperture rear sight. The early manufacture Auto-Ordnance, Bridgeport guns, like their Savage counterparts, were fitted with the finned barrel and the adjustable Lyman rear sight.
Auto Ordnance Search Serial Number WasĪ similar AO prefix serial number was applied to the rear of the trigger frame. The 1928A1 Thompson Submachine Guns being produced at Auto-Ordnances Bridgeport plant were identical mechanically and in appearance to those being made by Savage in Utica, New York.