1. 
   M61A1
   The General Electric M61A1 (Vulcan) is an American 20 mm calibre six-barrel Gatling gun mounted on the M163 AFV, and fitted to various aircraft. It has a variable rate of fire up to 6600 rounds per minute and a muzzle velocity of 1036 meters-per-second and fires APT ammunition with armour penetratio...
   Found op http://www.probertencyclopaedia.com/browse/FMM.HTM
   
   
2. 
   M61A1
   The General Electric M61A1 (Vulcan) is an American 20 mm calibre six-barrel Gatling gun mounted on the M163 AFV, and fitted to various aircraft. It has a variable rate of fire up to 6600 rounds per minute and a muzzle velocity of 1036 metres per second and fires APT ammunition with armour penetratio...
   Found op http://www.probertencyclopaedia.com/browse/IM.HTM
   
   

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