Model of Tommy-Gun, Thompson Submachine Gun, high poly model made in Blender 2.9 and textured in Substance Painter. Chicago Typewriter, Chicago Piano, Trench Broom, Tommy Gun. The Thompson submachine gun is a blowback-operated, air-cooled, magazine-fed selective-fire submachine gun, invented by the United States Army Brigadier general John T. Thompson in 1918. It was originally designed to break the stalemate of trench warfare of World War I, but was not finished until after the war ended.