The Brownells BRN-15 5.56MM 13.7'' BBL .750'' GAS BLOCK UPPER RECEIVER delivers a ready-to-build AR-15 upper that blends rugged government-contour aesthetics with proven 5.56x45mm NATO performance, featuring a 13.7" barrel, a .750" gas block, and a 1/2-28 muzzle thread to accommodate a wide range of silencers and compensators while preserving a compact profile for maneuverability. Finished in a durable black anodized coating, this assembled upper receiver aligns with AR-15 compatibility and a 1-7 twist rate to stabilize a broad spectrum of 5.56/.223 ammunition, making it suitable for reliable plinking, sport shooting, and close-to-mid-range engagements. The upper integrates seamlessly with standard AR-15 lowers, offering an efficient pathway to upgrade or complete a rifle build with consistent bolt carrier compatibility and a rigid, repeatable platform. Its government-contour barrel and precision-machined upper components contribute to accuracy and handling, while the streamlined design supports quick field maintenance and straightforward assembly. For shooters seeking a robust, in-stock option that emphasizes performance and compatibility, Brownells BRN-15 upper assemblies deliver a dependable foundation for reliable operation, custom user configurations, and versatile application across varmint, target, and defensive scenarios.