The Thompson models 1928, 1928A1, M1 and M1A1 submachine guns, famously also nicknamed the ‘Tommy Gun’, are a heavy weight milled all-steel submachine gun design, chambered in the U.S. military’s then standard issue pistol round – the .45 ACP cartridge, and designed in the USA in the wake of World War One. They were first adopted by the U.S. military in a widely used capacity during the World War Two, eventually being supplanted by the cheaper and simpler M3 and M3A1 ‘Grease-Gun’ submachine guns. A small but significant number have also been seen in the Pak-Afghan Region.