The story
Auto-Ordnance Corporation was created by John T. Thompson in August 1916 with the backing of investor Thomas Ryan. In 1915 Thompson had found the Blish Lock patent of Commander John Blish, which was the operating principle of the first prototypes of the Thompson submachine gun and the Thompson Autorifle. In exchange for shares of the newly founded company Blish agreed to give Thompson his patent. Thompson hired two design engineers Theodore H. Eickoff and Oscar V. Payne. The engineers learned that the Blish lock design, which was a delayed blowback action, was ineffective with the.30-06 rifle cartridge but very effective with the.45 ACP pistol round. The birth of the Thompson submachine gun took place when Thompson had the idea of a "trench sweeper" or "trench broom". The first short run production model was 1919, too late for use in World War I.
Thompson first showed the submachine gun design to the US government, but it became a gun for law enforcement before it was put to use in the military. The initial production of the Model 1921 was by Colt. After the Thompson submachine gun received the nickname "Tommy Gun" in the popular press, Thompson went to the trademark office to protect the nickname. A small run of M1928 and M1928A1 made by Savage Arms were stamped "TOMMY GUN".
From Wikipedia’s article on Auto-Ordnance Corporation, shared under CC BY-SA 4.0.3