The General Dynamics GAU-17/A Minigun (in-game stylized as Minigun) is a mounted heavy machine gun featured in Spec Ops: The Line.
The GAU-17/A is an electrically powered, six barrel rotary machine gun. Developed by General Electric, it was first fielded by the United States Armed Forces in the 1960s, seeing extensive use on helicopters and airplanes during the Vietnam War, as well as subsequent conflicts.
In The Line
The GAU-17/A is seen mounted in the doorway on most of the 33rd Infantry's Blackhawk helicopters. It is used against Agent Gould and his men during their assault on the gate and, later, is used by Captain Walker to defend Delta Squad's stolen helicopter during their escape from the Trans-Emirates Building, using it to shoot down numerous AH-6J Little Birds. This sequence appears in the game's prologue as well as end of Chapter 13. As such, the Minigun can be used at most twice during the game, with it being used at least once during Chapter 13.
It should be noted that, due to being electrically powered, the GAU-17/A doesn't overheat. Thus, it can be fired continuously, making both ground and airborne targets far easier to deal with.
Like the M2E2HMG, it has unlimited ammunition.