The GAU-19/A (GECAL 50) is an electrically driven, three-barrel rotary heavy machine gun that fires the .50 BMG (12.7×99mm) cartridge. Technical specifications The GAU-19/A is designed to accept standard NATO .50 caliber M9-linked ammunition. The rate of fire is selectable to be either 1,000 or 2,000 rounds per minute. The Humvee armament kit version fires at 1,300 rounds per minute. The average recoil force when firing is 1.7 kN, 2.2 kN or 2.8 kN depending on firing rate. In January 2012, General Dynamics announced they would be delivering a new version designated GAU-19/B. It provides the same firepower in a lighter platform, weighing and optimized for a firing rate of 1,300 rounds per minute and an average recoil force of 2.5 kN. Both variants can be configured for an ammunition capacity of 500–1,200 rounds. Both variants are reliable to 40,000 mean rounds between failure. History The GECAL 50 was first manufactured by General Electric, then by Lockheed Martin, and now by General Dynamics. Design work began in 1982. Early prototypes had six barrels, but a three-barreled configuration is now standard. The GAU-19/A was originally designed as a larger, more potent version of the M134 Minigun. Due to the loss of nine helicopters in Grenada, GE started building prototypes of the weapon in both a three-barreled and a six-barreled configuration. The six-barreled version was designed to fire 4,000 rounds per minute, and could be adapted to fire up to 8,000 rounds per minute. The GAU-19 takes 0.4 seconds to reach maximum firing rate. Soon it was recommended as a potential armament for the V-22 Osprey. The magazine would be located underneath the cabin floor and could be reloaded in-flight. However, plans to mount the gun were later dropped. In December 1992 the US Navy issued a letter of qualification for GAU-19/A integration and use on naval aircraft. In 2005, the GAU-19/A was approved to be mounted on the OH-58D Kiowa helicopter. It also could have been used on the Army's now cancelled ARH-70. In 1999, the United States sent 28 GAU-19s to Colombia. Oman is known to use the GAU-19/A mounted on their HMMWVs. The Mexican Navy uses MDH MD-902 series helicopters with the GAU-19/A system mounted for anti-narcotics operations. In October 2010 General Dynamics began developing the lighter weight GAU-19/B in response to an urgent needs statement issued by the Armed Scout Helicopter Program Office. By April 2011 flight testing