The Thompson is an American submachine gun chambered in .45 ACP.
The Thompson was favored by military soldiers, criminals, police and civilians alike for its ergonomics, compactness, large .45 ACP cartridge, reliability, and high volume of automatic fire. It has since gained popularity among civilian collectors for its historical significance.
Designed by John T. Thompson in 1919, the Thompson is perhaps best known for its use during the Prohibition Era in the United States of America, when it was employed by both law enforcement agencies and the bootleggers they were attempting to catch. It was during this time that the weapon earned its plethora of nicknames, including "Tommy Gun", "Trench Broom", "Trench Sweeper", "Chicago Typewriter", "Chicago Piano", "Chicago Style", "Chicago Organ Grinder" and "The Chopper". Later variants of the Thompson, namely the M1 and M1A1, were issued as standard to American NCOs and vehicle crews during World War II, and were also used by many other Allied nations during the war — notably, the British used a large number of Thompsons until production of their own Sten submachine gun caught up with demand.
Such was the popularity of the Thompson that the weapon continued to find use (on a strictly informal basis) long after it was pressed out of service with the United States military. In Vietnam, American troops often found themselves facing Viet Cong irregulars armed with the weapon, who favoured it for its simplicity and reliability. The Thompson also saw action in the Northern Ireland conflict and the Bosnian War.
In Alien3, the Thompson M1A1 was again the basis for the live-firing Pulse Rifle used in the film, although this time the Pulse Rifles were finished in black instead of the brown-green seen in the previous film.
In Aliens: Colonial Marines and Stasis Interrupted, the M41A appears once again, with elements of the Thompson still visible beneath the shroud. The new M41A Pulse Rifle MK2 also appears to be based on the M1A1, but is slightly modified and noticeably smaller.
- The Thompson was one of three World War II weapons used in the construction of the (mostly fictional) firearms seen in Aliens. The others were the MP 40 and the MG 42 (both German weapons). The use of mostly WWII-era weapons on the production was probably for practical reasons — large numbers of such weapons are in existence (Bapty & Co. has a huge selection of working WWII firearms), ammunition is generally cheap and plentiful, and their typically solid-steel construction means they can be easily fitted with cosmetic modifications.
- Such was the popularity of the M41A Pulse Rifle that over the years many aftermarket kits have been sold to convert airsoft Thompsons into replicas of the M41A as seen in Aliens.