Both use the same stainless steel firing pins and gas tubes, and many AR-15s use the M16's front sight post/gas block combo shown above.
Almost all AR-15 barrels are made from 4150 (CMV) steel used in the M16's barrel. The mil-spec AR and M16 use forged 7075-T6 receivers. Almost all their parts are directly interchangeable. These two rifles are nearly identical in materials and construction. The M4 carbine was later introduced, further blurring the lines between Stoner's semi- and fully automatic black rifles. 308-caliber AR-10, the smaller AR-15 was favored by military brass for its maneuverability, ammo capacity, and surprising wounding ability.Ĭolt re-designated the AR-15 the M16A1 and provided it for service in Vietnam in 1964. The M16 was made by Colt to be little more than a fully automatic AR-15 but today, there are loads of configurations available for both rifles. The rifle saw trials as part of a competition to replace the military's 7.62mm rifles. Based on the. Colt took the design and made some improvements to bolster accuracy and reliability. Facing financial difficulty, ArmaLite sold the AR-15 to Colt in 1959. This select-fire, air-cooled, gas-operated, magazine-fed rifle was designed to provide infantrymen with a new and lightweight rifle, one that could be carried more easily than the large 7.62mm NATO rifles then in use by the military. The AR-15 was designed in 1956 by Eugene Stoner of ArmaLite, an American small arms company based in California. So, what are the differences? Let's break down these sibling weapon platforms. These fully automatic rifles look identical to the typical AR-15. If you're a gun owner getting into the AR platform, you've already seen references to the M4 and M16, two military-issued rifles currently in service.