The Rock River Arms Tactical Carbine Complete Upper Receiver in 450 Bushmaster combines rugged reliability with modern AR-15 versatility, featuring a 16" barrel paired with a mid-length gas system for smooth cycling and improved accuracy. This Anodized Black upper includes the RRA Operator Muzzle Brake for controlled recoil, a 13" free-floating M-LOK handguard for versatile accessory mounting, and a precision-matched bolt carrier group and charging handle, delivering ready-to-fire performance straight from the box. Designed to fit AR-15 platforms, it accepts standard magazines and provides a 5-round capacity with one magazine included, making it a practical choice for hunters and tactical enthusiasts seeking a dedicated 450 Bushmaster upper with authoritative ballast and stability. The complete upper receiver emphasizes durability and corrosion resistance with an anodized finish, ensuring reliable operation in varied environments. Ideal for mid-range hunting, varmints, and woodland defense, this upper is a robust upgrade for building a dependable rifle that leverages the ballistic advantages of the 450 Bushmaster while maintaining compatibility with existing AR-15 components. Rock River Arms delivers a cohesive package that emphasizes fit, finish, and field-ready performance.