A Brownells AR-15 5.56mm bolt carrier group in nitride is the heart of a reliable AR-15 build or a smart spare to keep in your kit. Whether you're assembling your first rifle, completing a build, or just want a known-good BCG on the bench, this nitride-coated carrier delivers the durability and function serious shooters depend on. It's built to run in any AR-15 chambered for 5.56 NATO, .223 Remington, or 300 Blackout—essentially any rifle using a 5.56 NATO case family cartridge.

The bolt itself is machined from 9310 tool steel, heat-treated and shot-peened to handle the repeated firing cycle. The carrier is 8620 hardened steel. Both are finished with a nitride coating that resists corrosion and wear without the brittleness you'll find in some cheaper alternatives. Every bolt receives magnetic-particle inspection to catch defects before it ships, and the gas key arrives torqued and staked—no guessing whether it's tight enough. That kind of attention matters when reliability is non-negotiable.

The group comes complete: bolt, carrier, gas key, firing pin, cam pin, firing pin retaining pin, extractor, extractor spring, and extractor insert. You get everything needed to drop it into your lower receiver and run. This BCG is designed for semi-automatic use and is not compatible with full-auto lower receivers. Whether you're a builder, a range regular who rotates parts, or someone who just appreciates having a spare that's been vetted, a quality nitride-finished bolt carrier group from Brownells is a no-fuss choice.

A Brownells AR-15 5.56mm bolt carrier group in nitride is the heart of a reliable AR-15 build or a smart spare to keep in your kit. Whether you're assembling your first rifle, completing a build, or just want a known-good BCG on the bench, this nitride-coated carrier delivers the durability and function serious shooters depend on. It's built to run in any AR-15 chambered for 5.56 NATO, .223 Remington, or 300 Blackout—essentially any rifle using a 5.56 NATO case family cartridge.

The bolt itself is machined from 9310 tool steel, heat-treated and shot-peened to handle the repeated firing cycle. The carrier is 8620 hardened steel. Both are finished with a nitride coating that resists corrosion and wear without the brittleness you'll find in some cheaper alternatives. Every bolt receives magnetic-particle inspection to catch defects before it ships, and the gas key arrives torqued and staked—no guessing whether it's tight enough. That kind of attention matters when reliability is non-negotiable.

The group comes complete: bolt, carrier, gas key, firing pin, cam pin, firing pin retaining pin, extractor, extractor spring, and extractor insert. You get everything needed to drop it into your lower receiver and run. This BCG is designed for semi-automatic use and is not compatible with full-auto lower receivers. Whether you're a builder, a range regular who rotates parts, or someone who just appreciates having a spare that's been vetted, a quality nitride-finished bolt carrier group from Brownells is a no-fuss choice.