Rock River Arms Complete Mid-Length A4 Upper Receiver .450 Bushmaster 16" – AR-15 Platform

The Rock River Arms Complete Mid-Length A4 Upper Receiver delivers straight-wall cartridge performance in .450 Bushmaster for AR-15 lower receivers. This 16-inch configuration is purpose-built for hunters in straight-wall states and shooters seeking substantial stopping power at moderate range. The mid-length gas system provides reliable cycling with this hard-hitting caliber while managing recoil effectively.

Constructed from forged aluminum with a durable finish, this complete upper assembly arrives ready to install on any mil-spec AR-15 lower receiver. The A4 flat-top design accepts standard optics and iron sights. Installation requires no gunsmithing—simply attach to your lower receiver using standard takedown pins. Ships with a 5-round magazine to comply with hunting regulations in many jurisdictions.

• Caliber: .450 Bushmaster
• Type: Complete Upper Receiver Assembly
• Compatible Lower: Mil-spec AR-15
• Barrel Length: 16 inches
• Gas System: Mid-length
• Material: Forged aluminum upper receiver
• Configuration: A4 flat-top
• Includes: 5-round magazine
• Installation: Drop-in, no gunsmithing required