Rock River Arms has established a distinguished reputation for crafting high-quality firearms that are trusted by military personnel, law enforcement professionals, hunters and shooting enthusiasts across various disciplines. Their complete upper receivers offer a convenient solution for finishing rifle builds or quickly adapting calibers on your preferred AR-15 platform. This complete upper receiver is chambered in .450 Bushmaster, renowned for its power and versatility in hunting and tactical applications. It features a 16 inches chrome moly steel barrel equipped with a muzzle brake, effectively reducing felt recoil and enhancing accuracy for successive shots. Additionally, the upper boasts a lightweight aluminum free-float handguard with M-LOK slots, allowing seamless attachment of M-LOK compatible accessories such as bipods, foregrips and lights to customize your setup to meet specific shooting needs. Included with the upper are a bolt carrier group, charging handle and magazine, making it ready for direct attachment to any standard AR-15 lower receiver. This configuration provides a robust platform that blends Rock River Arms' renowned craftsmanship with the performance capabilities of the .450 Bushmaster cartridge, ensuring reliability and precision in diverse shooting scenarios.