Brand: Rock River Arms
Model: A4
Caliber: .450 Bushmaster
Platform: AR-15
Barrel: 16" 416R Stainless Steel, Cryogenically Treated
Color: Black
Gas System: Mid-Length
Muzzle Device: RRA Operator Brake
Muzzle Thread: 5/8-32
Twist: 1:24
Receiver: Anodized
Handguard: RRA 13" Ext. Lightweight
Attachment Style: M-Lok
BCG: Yes
Charging Handle: Yes
Weight: 4.47 lbs
Length: 24"

Features

Rock River Arms is known for delivering reliable, high-performance firearms trusted by military, law enforcement, hunters, and shooting enthusiasts alike. This complete .450 Bushmaster upper is built for versatility and stopping power. It features a 16" stainless steel barrel with a muzzle brake to reduce recoil and improve accuracy during rapid follow-up shots.

A lightweight aluminum free-float M-LOK handguard allows for easy accessory attachment, while the included bolt carrier group, charging handle, and magazine make this upper ready to drop onto any standard AR-15 lower. Rugged, accurate, and adaptable, this setup is ideal for those looking to harness the full potential of the .450 Bushmaster.

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Shipping Restrictions

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.