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 fowling or residue, and other minor adjustments. This particular rifle integrates some later features, like the closed-bottom bird cage flash hider and the 6-position telescoping buttstock. Post front and two-leaf flip rear sights, with "C MP B" on the underside of the barrel. The right side of the upper receiver has the "VP" triangle stamp at the front and "C H" below the windage adjustment dial, with the Rampant Colt, model marking, and address on the left side of the lower receiver. The selector is right handed, with "SAFE", "SEMI" and "AUTO" positions, all functional. Fitted with a checkered pistol grip and the aforementioned 6-position buttstock. Magazine absent.