ACME GAU-21 Gun Active Recoil System

ACME GAU-21 Gun Active Recoil System

• Aircraft Variant of the M3 Heavy Machine Gun
• United States
• Current: General Dynamics
• United States Marine Corps
• United States Marines (Pathfinder)


ACME produces GAU-21 M3 machine gun simulators that give the full-force, full rate of recoil feel of the actual weapon in a full scale gun replica that can be mounted on any aircraft, watercraft or vehicle simulator.  Our machine gun simulators use a unique, patented all-electric Gun Active Recoil system within the mounting cradle to provide the recoil. ACME’s gun active recoil is the only weapon training system available anywhere that provides training critical, full force recoil using an electric system.  ACME produces unique machine gun weapon training systems that feature full-force, all-electric recoil at full rate of fire.  ACME’s weapon training systems combine highly realistic replica (non-weapon) guns, our patented, Gun Active Recoil System (GAR®) weapon cradle, and the electronics to drive it.

During World War II, a faster-firing Browning was developed for aircraft use. The AN/M3 features a mechanical or electrically boosted feed mechanism to increase the rate of fire to around 1,200 rounds per minute. The AN/M3 was used in Korea on the F-86 Sabre, F-84 Thunderjet and F-80 Shooting Star, and in Vietnam in the XM14/SUU-12/A gun pod. Today, it can be found on the Embraer EMB 314 Super Tucano.

The M3-series is used by the U.S. military in two versions; the M3M and M3P. The fixed, remote-firing version, the FN M3P, is employed on the Avenger Air Defense System, and is currently being used on the OH-58D; augmenting the XM296 .50 cal. machine gun.  The M3M flexible machine gun has been adopted by USN under the designation GAU-21/A for use on helicopters. The GAU-21/A is also being used by the United States Marine Corps to upgrade from the XM-218/GAU-16 .50 cal. machine gun for the CH-53E, on the UH-1Y Venom, and on the Canadian Forces’ CH-146 Griffon via the INGRESS upgrade.

Standard GAR® Simulator Features:

ACME Gun Active Recoil Simulators offers many standard base features for your Gun solutions.

  • Realistically replicates recoil motion, frequency, and intensity
  • Adaptable to ANY small arms weapon or trainer
  • Works directly with the existing weapon system trainer/simulator firing signals
  • Electric motors eliminates expensive blank rounds and maintenance intensive pneumatic systems
  • Variable intensity to fine tune recoil
  • Easy access to system components for maintenance and tuning
  • Ruggedized systems available to adapt actual weapons for field use
  • Actual Handles and Triggers
  • 120VAC 15A Wall Power or 12/24VDC from Vehicles

Available GAR® Simulator Ancillary System Options:

ACME can provide ancillary systems to expand the base features for your advanced Gun solutions.

  • Laser Illumination/Targeting – The weapon supports laser mounted targeting for visual tracking of weapon aim points and student understanding of recoil compensation.
  • Windloading System – Puts variable resistance on the gun based on simulated air speed and the weapon’s angle of attack to the air stream (for helicopter door gunner sims).
  • Ammunition Countdown System – Ensures that trainees cannot spray bullets without regard for realistic limits.
  • Ammunition Belted System – The GAR™ can cycle ammunition belts through the gun for added training and realism.
  • Visual Muzzle Flash System – The GAR™ can have lighted muzzle flash physically added for cueing, training and realism. Visibile or IR spectrum.
  • Gun Mount Systems – Your GAR™ can be fitted to cover any standard Military Gun Mount; Mk64, Mk93, Mk97, etc.
  • Gun Use Sensor Systems – Your GAR™ can have various sensors integrated for Student Monitored Inputs such as:
  • Proper Charge Position and Use
  • Ammunition Change-Out Actions
  • Azimuth and Elevation Mount Sensors


Malfunctions Options:

Since the weapon responds to external firing signals, we can support a wide range of malfunctions.

  • Runaway – The weapon continues to fire even when the trigger is released. Standard response to run away is to keep the weapon pointed to safe location and perhaps break the ammunition belt to limit the rounds available for runaway.
  • Round Cookoff – When the gun is hot, ammunition can self-fire. The gun could replicate this by erratic, sudden, or unintended recoil regardless of trigger position.
  • Misfire – The weapon can fail to fire for one or multiple cycles. Response to this might be to cycle the charge handle to jack the offending round from the breach.
  • Equipment Jams – The weapon can stop firing even with ammunition present. Response might be lift the top cover, remove the belt, cycle charge handle, reset ammo, and recharge the weapon.
  • Firing Degradation – When the weapon gets hot and dirty, the rate of fire can significantly slow and the number of jams/misfires increases significantly. Defective ammunition is also another potential cause and these have different training responses for the gunner