Introduced in 1967, the M16A1 (aka the Model 603) would be the standard issue rifle for the United States Army and Marine Corps until the 1980s. Developed from end-user feedback on the M16, the M16A1 introduced the "fenced" magazine catch to reduce the risk of accidentally ejecting the magazine during handling or movement, the forward assist upper receiver and bolt to help close a bolt that is obstructed by fouling or residue, and other minor adjustments. This example has been fitted with an Ares Defense Systems Shrike 5.56 upper receiver, converting it into a piston driven closed bolt belt fed machine gun with an A2 flash hider on the quick detach barrel, adjustable post front sight, quad rail forearm, non-reciprocating side mounted charging handle, and an L3 EOTech dot sight and flip-off magnifier unit combo on the flip-top cover. The receiver has the M16A1 nomenclature and serial number on the left side of the magazine well, with "SAFE", "SEMI" and "AUTO" markings around the right handed selector, checkered pistol grip and a four-position telescoping buttstock. The bolt is properly configured for compatibility with the Shrike upper and the auto sear, with a matte black finish. Included with the lot is one unmarked magazine, backup rear sight, vertical foregrip, cheek rest, and other small parts.

Excellent, with 95% plus matte black phosphate finish, showing some light handling marks overall, concentrated on the lower receiver. The furniture is also excellent. The magnifier is clear, though the dot sight is untested. Mechanically excellent. NOTE: This weapon is a National Firearms Act (NFA), fully transferable Class 3, which is registered with the Bureau of Alcohol, Tobacco, Firearms and Explosives, (BATFE) that is classified as a "Curios or Relic" as defined in 27 CFR, 478.11. These weapons are still subject to the provisions of 18 U.S.C. Chapter 44 and 27 CFR part 479.