Brn-15 11.5'' Upper Receiver Assembly .750'' Gas Block 5.56mm

The Brn-15 11.5'' Upper Receiver Assembly .750'' Gas Block 5.56mm is a proven short-stroke combat carbine upper built for operators who demand compact firepower without sacrificing reliability. This upper receiver assembly from Brownells serves law enforcement, military personnel, and serious tactical shooters who require a short-barreled platform for close-quarters operations, vehicle transport, or breaching environments. At 11.5 inches, this barrel length delivers the velocity stability needed for 5.56mm NATO while remaining substantially more maneuverable than full-length uppers in tight spaces.

The .750-inch diameter gas block is engineered to meter propellant gas efficiently through a short-stroke system, ensuring consistent bolt carrier acceleration even with suppressed fire or when running subsonic ammunition. This geometry reduces felt recoil and accelerates the gun into target acquisition for the next shot—critical advantages in dynamic tactical scenarios. The complete upper assembly integrates the barrel, gas tube, bolt carrier group, and charging handle into a drop-in ready unit that simplifies installation and maintains tight tolerances. Weighing 3.4 pounds, it remains lightweight enough for extended operations while delivering the precision fit and dimensional accuracy that Brownells is known for across law enforcement and military supply channels.

This upper receiver assembly is compatible with any AR-platform lower receiver in .223 Remington or 5.56mm NATO, making it an ideal upgrade or replacement for SBR builds, CQB platforms, and reconfigurable duty rifles. Operators who have cycled comparable short-stroke uppers report faster target transitions and reduced muzzle rise compared to longer barrels, especially in confined spaces where maneuverability matters. Installation requires no gunsmithing—simply lock the upper onto your lower receiver and you're ready to run. Whether you're building a suppressed precision gun, a dedicated entry weapon, or a backup carbine, the Brn-15 11.5'' Upper Receiver Assembly delivers combat-tested performance in a compact package.