The AR-10 is an American-designed 7.62x51mm NATO battle rifle, developed in 1955 by Eugene Stoner at ArmaLite. The AR-10 was one of the lightest battle rifles ever made due to its heavy use of aluminum and fiberglass, yet also one of the most controllable in fully automatic fire due to its straight-line stock design (then a relatively new concept, but now almost universal). The AR-10 was rejected by the US Army in favor of the more conventional M14 and was used only by a handful of small foreign armies, but two years later it served as the basis for the M16 assault rifle.
This tag implicates battle_rifle (learn more).