The M240, officially the Machine Gun, 7.62 mm, M240, is the US military designation for the FN MAG (Mitrailleuse A Gaz, gas-operated machine gun; alternatively, Mitrailleuse dAppui General machine gun, support, general), a family of belt-fed, gas-operated medium machine guns that chamber the 7.62×51mm NATO cartridge.
The M240 has been used by the United States Armed Forces since the late 1970s. It is used extensively by infantry, most often in rifle companies, as well as on ground vehicles, watercraft and aircraft. Despite being heavier than some comparable weapons, it is highly regarded for reliability and its standardization among NATO members is a major advantage.
All variants are fed from disintegrating belts and are capable of firing most types of 7.62 mm (.30/.308 cal) NATO ammunition. M240 variants can be converted to use non-disintegrating belts. There are significant differences in weight and some features among some versions which restrict interchangeability of parts. The M240s used by the US military are currently manufactured by FN America, the American subsidiary of FN Herstal.
The M240B and M240G are usually fired from integrated bipods, tripods, or vehicular mounts; regarding tripod use, the U.S. Army primarily uses the M192 lightweight ground mount, while the U.S. Marine Corps uses the M122A1 tripod, a slightly updated M2 tripod.