Marines with Marine Heavy Helicopter Squadron 462 conducted a GAU-21 weapons shoot from CH-53E Super Stallions.


FN M3M (GAU-21)

The FN M3M (GAU-21) is a .50 caliber (12.7x99mm) single barrel rapid-fire machine gun suitable for rotary-wing aircraft applications providing defensive firepower ranging out to nearly 2000 meters.

The FN M3M was designated by the U.S. Navy as the GAU-21 in 2004 and is currently used by all services within the U.S. Department of Defense (DoD). An evolution of the M3 .50-caliber heavy machine gun, it produces a blistering 1,100 rounds per minute cyclic rate of fire through the use of open-bolt operation and a dual recoil buffer system. Operating independent of either electrical or hydraulic power sources, the FN M3M/GAU-21’s unique soft mount system enhances weapon accuracy and minimizes the firing vibration transmitted to the airframe.



FN M3M (GAU-21)

  • 50 BMG (12.7x99mm) NATO
  • Full auto
  • Short-recoil operated
  • Open-bolt design
  • 950-1100 rounds per minute (RPM) cyclic rate




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