Thompson submachine gun
The Thompson submachine gun, also known as the Tommy gun, was a popular submachine gun that became (in)famous during prohibition. Gangsters would use it because the compact firearm has a high volume of automatic fire and it could be obtained legally.
Designed during World War I by General John T. Thompson, the Tommy gun was available in the .45 Caliber ACP (Automatic Colt Pistol) cartridge, and was used by the U.S. Army and British Commandos through World War II. The means of operation is direct blow-back, although early models made use of the Blish lock, turning the mechanism into a delayed blow-back system. After WWII it saw limited service in Korea, and was carried unofficially by a smattering of soldiers in Vietnam.
The Thompson went through numerous changes while in military service during WWII, almost all directed at reducing its high cost and time-consuming manufacturing time. It was eventually replaced mid-war with the M3 "Grease Gun".
In the United States, it was used by law enforcement, most prominently by the FBI, until 1976 when it was declared obsolete, and all Thompsons in government possession were destroyed, except for a few token museum pieces and training models. Owing to both its gangster and WWII connections, Thompsons are highly sought after collector's items. An original 1928 gun in working condition can easily fetch $15,000. Semi-auto replicas are currently produced by the Auto-Ordnance Company, which is operated as a division of Kahr firearms.
Soon time, during and after recruitment processes were taken up by the US Military, supply shortages at the time forced soldiers to sometimes bring their own firearms to combat, and not until 1943 did the US have a firm grip on production and manufacturing of firearms.
Approx. 1,700,000 of these weapons were produced, 1,387,134 of them being part of the M1 series.