Thompson M1928A1

Thompson Submachine Gun, Caliber .45
M1928A1 Thompson wartime production variant
Type	Submachine gun
Place of origin	United States
Service history
In service	1938–1971 (officially, U.S. military) 1938–present (other countries)
Used by	See Users
Wars	Banana Wars Irish Civil War World War II Indonesian National Revolution Chinese Civil War First Indochina War Greek Civil War Korean War Vietnam War The Troubles Bosnian War and numerous others
Production history
Designer	John T. Thompson
Designed	1917–1920
Manufacturer	Auto-Ordnance Company (originally) The Birmingham Small Arms Company Limited Colt Savage Arms RPB Industries
Produced	1921–1945
No. built	Approx. 2,000,000
Variants	See Variants section
Specifications
Weight	10.8 lb (4.9 kg) empty (M1928A1) 10.6 lb (4.8 kg) empty (M1A1)
Length	33.5 in (850 mm) (M1928A1) 32 in (810 mm) (M1/M1A1)
Barrel length	10.5 in (270 mm) 12 in (300 mm) (with Cutts compensator)
Cartridge	.45 ACP (11.43×23mm)
Action	Blowback, Blish Lock
Rate of fire	600–725 rpm (M1928), 700 rpm (M1A1), 1500 rpm (M1919)
Muzzle velocity	935 ft/s (285 m/s)
Effective firing range	150m
Feed system	20-round stick/box magazine 30-round stick/box magazine 50-round drum magazine 100-round drum magazine (M1 and M1A1 models do not accept drum magazines)

1938–1971 (officially, U.S. military)

The Thompson submachine gun is an American submachine gun, invented by John T. Thompson in 1918, that became infamous during the Prohibition era. It was a common sight in the media of the time, being used by both law enforcement officers and criminals. The Thompson submachine gun was also known informally as the "Tommy Gun", "Annihilator", "Chicago Typewriter", "Chicago Piano", "Chicago Style", "Chicago Organ Grinder", "Trench Broom", "Trench Sweeper", "The Chopper", and simply "The Thompson".

The Thompson was favored by soldiers, criminals, police, and civilians alike for its large .45 ACP cartridge, accuracy, and high volume of automatic fire. It has since gained popularity among civilian collectors for its historical significance. It has had, and continues to have, considerable significance in popular culture, especially in works about the U.S.'s Prohibition era and World War II, and hence is among the best-known firearms in recent history. Although the original fully automatic Thompsons are no longer produced, numerous semi-automatic civilian versions are still being manufactured by Auto Ordnance. These retain a similar appearance to the original models, but they have various modifications in order to comply with US firearm laws.

The Thompson Submachine Gun was developed by General John T. Thompson who originally envisioned an "auto rifle" (semi-automatic rifle) to replace the bolt action service rifles then in use. While searching for a way to allow such a weapon to operate safely without the complexity of a recoil or gas operated mechanism, Thompson came across a patent issued to John Bell Blish in 1915 based on adhesion of inclined metal surfaces under pressure. Thompson found a financial backer, Thomas F. Ryan, and started the Auto-Ordnance Company in 1916 for the purpose of developing his "auto rifle". It was primarily developed in Cleveland, Ohio. The principal designers were Theodore H. Eickhoff, Oscar V. Payne, and George E. Goll. By late 1917, the limits of the Blish Principle were discovered: rather than working as a locked breech, it functioned as a friction-delayed blowback action. It was found that the only cartridge currently in U.S. service suitable for use with the lock was the .45 ACP round. Thompson then envisioned a "one-man, hand-held machine gun" in .45 ACP as a "trench broom" for use in the ongoing trench warfare of World War I. Payne designed the gun itself and its stick and drum magazines. The project was then titled "Annihilator I" and by 1918, most of the design issues had been resolved. However, the war ended two days before prototypes could be shipped to Europe.