Very little information exists of the T249 Vigilante and its T250 cannon. The conceptual design for the T250 cannon was initiated in 1956. While the design of cannon of this caliber would ordinarily be handled by
Watervliet Arsenal, it was decided that Springfield Armory would take responsibility due to their previous development experience with smaller caliber rotary cannon such the 20mm
T171. The T250 was the largest Gatling gun ever assembled. Its 37×219mmSR round was based upon a shortened and necked-down 40×311mmR Bofors cartridge case. Hydraulically powered, the gun was able to vary between 120 rpm for (especially stationary) ground targets and 3,000 rpm for air targets. It had a 192-round
drum magazine, which in the maximum 3,000 rpm mode would have equated to approximately 4 seconds of fire. When Springfield engineers finished their work in 1962, the design was handed over to Watervliet for production. The
Sperry Utah Engineering Laboratory was selected to handle the integration of the T250 gun with the modified M113 chassis to create the T249. ==Surviving Examples==