The infamous “chopper,” so often hidden in violin cases, in gangster
movies, takes its name from the patronym of one of its inventors, American
army officer John T. Thompson (1860-1940). Thompson and Navy Commander
John N. Blish invented the .45 caliber portable automatic weapon during
World War I and much improved it in later years. Gangsters and reporters
popularized the nickname tommygun in expressions like torpedo, triggerman,
bathtub gin, hideout, hijacker, to muscle in, and to take for a ride.
Although tommygun originally identified the Thompson machine gun, with its
pistol grip and shoulder stock, the term is now used to describe any
similar lightweight weapon with a drum-type magazine. The Thompson was
developed too late to be of use in World War I – when an estimated 80
percent of casualties were caused by heavy machine gun fire – but like the
British sten gun was employed by Allied troops in World War II. Because of
their short barrels, about thirty inches, most submachine guns are
relatively inaccurate except at close range. They weigh from six to twelve
pounds and hold twenty to fifty shots.