The AR-15 is based on the 7.62 mm AR-10 designed by Eugene Stoner, Robert Fremont, and L. James Sullivan of the Fairchild Armalite corporation. The AR-15 was developed as a lighter, 5.56 mm version of the AR-10. The 'AR' in all ArmaLite pattern firearms simply stands for 'ArmaLite Rifle', and can be found on most of the company's firearms: AR-5, a .22 caliber rifle; the AR-7, another .22 caliber; the AR-17 shotgun; the AR-10 rifle; and the AR-24 pistol. The AR-15 was first built in 1959 by ArmaLite as a small arms rifle.