Hey MORON. The AR-10 (.308) was out in 1957 designed by aerospace engineer Eugene Stoner. Then he built the .223 version (AR-15) to show it off to the military as a prototype before the full-auto version was ready for testing and that came out on the civilian market in 1964.
AR does NOT stand for "Assault Rifle" (it's not because there's no select-fire switch) but for Armalite Rifle.
Ray from Bloombergia
Soli Deo Gloria!!