The Minigun is a 5.56x45mm NATO, multi-barrel machine gun with a very high rate of fire (usually ranging from 2,000 to 6,000 rounds per minute), employing Gatling-style rotating barrels with an external power source. In popular culture, the term "minigun" has come to refer to any externally-powered Gatling gun of rifle caliber, though the term is sometimes used to refer to guns of similar rates of fire and configuration, regardless of power source and caliber. Specifically, minigun refers to a single weapon, originally produced by General Electric. The "mini" of the name is in comparison to designs that use a similar firing mechanism but larger shells, such as General Electric's earlier 20 mm M61 Vulcan.