The GAU-21 is a .50 caliber, single barrel, rapid-fire machine gun used on the Fleet Air Arm’s MH-60R. The GAU-21 provides both offensive and defensive firepower ranging out to nearly 2000 meters.

An evolution of the FN M3 .50 caliber heavy machine gun, it uses an open-bolt operation and a dual recoil buffer system. Operating independent of either electrical or hydraulic power sources, the GAU-21’s unique soft mount system enhances weapon accuracy and minimizes the firing vibration transmitted to the airframe.


Function Heavy Machine Gun
Manufacturer Fabrique Nationale Herstal (FN Herstal)
Designed 2004
Operation Short Recoil
Modes Fully automatic
Feed Belt-fed
Rate of fire 950-1,100 rounds per minute
Ammunition Ball and tracer
Calibre 50 BMG (12.7 x 99mm) NATO
Range 2000m (maximum effective)


Small arms