Tweet   The 5 barrels Equalizer is likely the most balanced weapon of the entire Gatling family. It fires a heavier, harder hitiing projectiles than the 20mm Vulcan/Phalsnx and is lighter than huge 30mm Avenger/Goalkeeper.  The five-barrel 'Equalizer' cannon was developed in the late 1970s, based on the mechanism of the GAU-8/A Avenger cannon, but firing a new NATO series of 25 mm ammunition. The GAU-12/U cannon is operated by a 15 hp (11 kW) electric motor, in external mounts supplied by a bleed air driven pneumatic system. Its rate of fire is normally 3,600 rounds per minute, with a maximum of 4,200 rounds per minute. For the AC-130, the fire rate was lowered to 1800 rounds per minute in order to conserve ammunition. The Equalizer normally uses PGU-20/U armor-piercing incendiary (API) or PGU-22 or PGU-25 high explosive incendiary (HEI) ammunition. With a harder-hitting projectile and comparable muzzle velocity, it is more lethal than the older M61 Vulcan, more effective than the older 30 mm ADEN cannon it replaces, but not as effective and lethal as the Mauser BK-27[citation needed]. [edit]Current uses The current principal application for the Equalizer is the AV-8 Harrier IIs of the United States Marine Corps, Italian Navy and Spanish Navy. The Harrier II carries the Equalizer system in a pair of pods mounted on the fuselage sides, with the cannon in the port pod and 300 rounds of ammunition in the starboard pod, fed through a bridge at the aft ends of the pods that also contains the drive system for the gun. The complete installation, which includes a double-ended feed system that returns empty cartridges to the magazine, weighs 900 lb (410 kg) empty and 1,230 lb (560 kg) loaded. RAF and Fleet Air Arm Harriers have not adopted the Equalizer for their Harrier GR7 and GR9s. The British had originally planned a pair of ADEN 25 guns (using the same ammunition as the GAU-12/U, but based on the 30 mm ADEN cannon). That gun was canceled in 1999 a...