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.

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It is the customer’s responsibility for understanding state laws regarding all purchases made. For a comprehensive list of all Shipping Restrictions, please refer to our Shipping Restrictions By State Page found Here.

All NFA Rules Apply

These items are controlled by the U.S. Government and authorized for export only to the country of ultimate destination for use by the ultimate consignee or end-user(s) herein identified. They may not be resold, transferred, or otherwise disposed of, to any other country or to any person other than the authorized ultimate consignee or end-user(s), either in their original form or after being incorporated into other items, without first obtaining approval from the U.S. government or as otherwise authorized by U.S. law and regulations.

Local Law Compliance

Certain firearm parts and accessories, including AR-style upper receivers, are subject to complex and frequently changing federal, state, and local laws and regulations. While an upper receiver may be lawfully sold and shipped as a component, the legality of possessing, assembling, configuring, or using an upper receiver in certain states (e.g., California, Washington State) and localities depends on how it is assembled, combined with other components, and ultimately used. You are solely responsible for ensuring that any assembly, configuration, possession, or use complies with all federal, state, and local laws, including any so-called “assault weapon” bans and short-barreled rifle restrictions. We do not provide legal advice and are not responsible for unlawful configurations or uses.