Brownells M16 458 Socom/450 Bushmaster Bolt Carrier Group Nitride

The Brownells M16 .458 SOCOM/450 Bushmaster bolt carrier group is a purpose-built, complete carrier assembly for AR platform rifles chambered in these heavy-hitter intermediate cartridges. Whether you're running .458 SOCOM for maximum stopping power on medium to large game or the .450 Bushmaster for its efficiency in shorter barrels, this carrier is engineered to handle the higher pressures and demands of magnum rifle rounds without compromise.

Construction starts with a 9310 steel bolt head that's been heat-treated and shot-peened to withstand the stress of these cartridges, paired with a hardened 8620 steel carrier body. Every unit undergoes magnetic particle inspection to catch any internal flaws before it ships. The black-nitride finish adds corrosion resistance in the field, and the gas key comes torqued and staked from the factory—no guesswork, no adjustments needed out of the box.

You get the complete assembly: bolt, carrier, firing pin, cam pin, and firing pin retaining pin. The extractor features a durable rubber insert and spring for reliable extraction cycle after cycle. This is the kind of attention to detail that makes the difference when you're running a specialized upper receiver in a big-bore AR platform.

Key Features

• 9310 steel bolt head with heat treatment and shot peening for durability under magnum pressures
• 8620 steel carrier body, hardened and machined for reliability
• Black-nitride finish for improved corrosion resistance
• Torqued and staked gas key—ready to use as-is
• Magnetic particle inspection performed on every unit
• Complete assembly includes firing pin, cam pin, and firing pin retaining pin
• Extractor with rubber insert and spring for consistent performance

Specifications

Frequently Asked Questions

Will this bolt carrier group work with my .458 SOCOM upper?

Yes. This Brownells M16 bolt carrier group is designed to function in both .458 SOCOM and .450 Bushmaster AR-15 uppers.

What's included in this assembly?

You receive a complete bolt carrier group with the bolt, carrier body, firing pin, cam pin, and firing pin retaining pin. The gas key arrives torqued and staked, so it's ready to install in your upper receiver.

Why does the bolt use 9310 steel?

9310 steel is chosen for its toughness and ability to withstand the extreme pressures generated by magnum cartridges like .458 SOCOM and .450 Bushmaster. The heat treatment and shot peening further strengthen it for reliable long-term service.

Is the gas key staked?

Yes, the gas key comes torqued and staked from Brownells, eliminating the need for adjustment or additional staking during installation.