Primary Weapon Systems

Overview

The Primary Weapons Systems MK111 MOD 1-M Upper Receiver is a complete assembly designed for the AR-15 platform, chambered in 7.62x39mm. With an 11.85-inch barrel and a pistol-length gas system, this upper offers a compact design that enhances maneuverability while still delivering reliable performance. The 1:10 twist rate is optimized for stabilizing a variety of bullet weights, making it versatile for different ammunition types. This upper receiver is often found in short-barreled, tactical builds where both weight and compactness are critical.