Rock River Arms A4 Mid 450 Bushmaster 16" Upper
Complete upper receiver in 450 Bushmaster with 16" chrome moly barrel, mid-length gas system, free float M-LOK handguard, and operator muzzle brake. Includes bolt carrier group, charging handle, and magazine.
Rock River Arms A4 Mid-Length Upper Receiver
This complete upper receiver from Rock River Arms represents a thoughtful approach to the 450 Bushmaster platform. The rifle is chambered in 450 Bushmaster, a cartridge that delivers substantial power in an AR-15 format—ideal for hunting and defensive applications where terminal performance matters.
Barrel and Gas System
- 16" chrome moly barrel with 1:24 twist rate optimized for 450 Bushmaster projectiles
- Mid-length gas system provides balanced recoil impulse and reliability
- Properly dimensioned for the cartridge's pressure curve
Handguard and Ergonomics
The 13" free float M-LOK compatible handguard allows you to mount accessories exactly where you need them. Free floating design minimizes contact with the barrel, supporting accuracy potential. The M-LOK system has become the modern standard for modular mounting.
Muzzle Device
The Rock River Arms Operator Brake features a 5/8-32 thread pattern and is designed to manage recoil while maintaining control. This is a functional choice for a cartridge with the 450 Bushmaster's energy level.
Complete Package
This upper arrives ready to function. It includes:
- Bolt carrier group
- Charging handle assembly
- Five-round magazine
Simply attach to your AR-15 lower receiver and you're ready to work. The anodized black finish provides durable corrosion resistance for field use.
Features
- .450 bushmaster
- 16 inch chrome moly, 1:24 twist
- rra operator brake, 5/8-32 thread
- low profile gas block, mid-length gas system
- rra 13 inch extended lightweight free float rail
- bolt carrier group, charging handle assembly
- (1) magazine, (5) rounds
