Cruising over the desert just above 400 feet, a Marine crew chief kneels behind the Gun Ammunition Unit 21 mounted on the ramp of the CH-53D Sea Stallion. The pilots and crew chiefs in the front of the aircraft relay the current target’s location that will be coming into his field of fire within seconds.
Marine Heavy Helicopter Squadron 463, Marine Aircraft Group 16 (Reinforced), 3rd Marine Aircraft Wing, is the first CH-53D helicopter squadron to install the GAU-21 .50-caliber machine gun system onto their aircraft.
“The GAU-21 is very similar to the XM-218 .50-caliber, which is the machine gun that is mounted on the doors of the aircraft,” said Cpl. Thomas D. Martinez, crew chief and weapons and tactics instructor, HMH-463. “Most people can’t really tell the difference until they know a little bit about them. It is a new system to the Marine Corps. The XM-218 has been around forever, but the GAU-21 is modified to fire faster and fire slightly farther.”
This next paragraph is sure to resonate with MO readers:
“The 7.62 round used in the M-240G is too small,” said Harquail, a 26-year-old native of Sea Side, New Brunswick, Canada. “The rotor wash from the aircraft affects the rounds’ trajectory. The .50-caliber is a heavier round. You need a heavy round with a higher volume.”
Between the muscle required to man the weapon and the buffeting and heat in the rear of the aircraft, the crew chief has his work cut out for him. But they appreciate the weapon’s capability and location.
“We are normally engaged by the enemy from the rear of the aircraft,” said Martinez, a Durango High School graduate. “These weapons are important because our window guns only give us coverage in less than a 180 degree angle in front. The tail gun provides 180 degrees of coverage behind and to the sides of the aircraft.”