The Brownells BRN-15 upper receivers in 5.56mm NATO deliver a ready-to-build platform with an 11.5" government-contour barrel and a .750" gas block, crafted in anodized black for durable, long-lasting performance. Designed for AR-15 compatibility, this assembled upper receiver set brings together precision-fit components to support reliable cycling with 5.56x45mm NATO cartridges, while the 1/2-28 muzzle threading accommodates a wide range of compatible suppressors and devices. The twist rate of 1-7 ensures stable stabilization of modern, high-performance ammunition, making it an excellent choice for compact rifles and duty-style builds where quick handling and consistent accuracy matter. With its clean, integrated BAR-coded finishes and rugged construction, the BRN-15 upper gives shooters a dependable platform for plinking, varmint control, or sport shooting, allowing easy installation onto standard AR-15 receivers. This assembled upper is ideal for builders seeking a complete, ready-to-run upper assembly that blends traditional AR-15 ergonomics with Brownells trusted engineering, delivering a cohesive, high-performance upgrade for your rifle project.