The Rock River Arms RRA 450B0461 450 BM Mid A4 Upr Half SS Upper is a complete .450 Bushmaster upper built around a forged A4 receiver and a 16 inch stainless steel heavy barrel. The barrel is cryogenically treated and capped with the RRA Operator Brake on 5/8-32 threads, while a 13 inch extended lightweight free float M-LOK handguard provides ample rail space and a rigid, modern profile.

This upper is ready to drop onto a compatible AR-15 lower for hunting, range work, or general training where the .450 Bushmaster cartridge’s performance is desired. The mid-length gas system with low profile gas block helps maintain smooth cycling, and the included bolt carrier group, charging handle assembly, and 5 round magazine make it a straightforward way to configure a large-bore AR. Rock River Arms’ reputation for solid machining and thoughtful design is reflected throughout this upper.

Key Features:

• Manufacturer: Rock River Arms
• Model: RRA 450B0461 450 BM Mid A4 Upr Half SS Upper
• Caliber: .450 Bushmaster
• Condition: New
• Barrel Length: 16"
• Number of Magazines: 1
• Capacity: 5
• Threaded Barrel: Yes, 5/8-32
• What's In The Box: Complete upper, bolt carrier group, charging handle assembly, 5 round magazine
• Weight: 4.47 lbs
• Length: 24"