The Faxon Superfinished 5.56 M16 Bolt Carrier Group (FF556BCGCNITRIDE) is a complete drop-in AR-15 bolt carrier group chambered for 5.56 NATO, built for AR builders, competitive shooters, and hard-use rifle owners who want a domestically manufactured BCG that goes beyond mil-spec material selection, inspection, and surface finishing. This 5.56 NATO M16-pattern bolt carrier group for AR-15 builds and high round-count rifle use combines a 9310 tool steel bolt, salt bath nitride treatment, and a Superfinished carrier body into a ready-to-install assembly that fits any mil-spec AR-15 upper receiver.
Key Features
- Part number: FF556BCGCNITRIDE
- Caliber: 5.56 NATO, compatible with .223 Remington
- Bolt material: 9310 tool steel
- Carrier profile: M16 pattern, full-auto compatible
- Finish: Salt bath nitride on bolt and carrier
- Carrier body: Superfinished
- Inspection: Magnetic Particle Inspection (MPI) on bolt
- Heat treatment: Full mil-spec
- Shot peening: Mil-spec
- Extractor: S7 tool steel
- Extractor assembly: Spring, insert, and Crane O-ring installed
- Gas key fasteners: Grade 8, fully staked
- Forward assist serrations: Yes
- Weight: 11.4 oz
- Platform: AR-15
- Made in USA
Special Features
- The 9310 tool steel bolt exceeds the carbon steel content of mil-spec 158 tool steel, providing higher tensile strength and fatigue resistance at the lug roots where bolt failures most commonly initiate during high round-count and high-pressure firing cycles
- Salt bath nitride treatment penetrates the surface of both the bolt and carrier to increase case hardness, corrosion resistance, and lubricity simultaneously, producing a treatment that performs in the surface layer rather than sitting on top of the metal where it can wear through
- Faxon's proprietary Superfinish process reduces the surface roughness of the carrier body below what standard machining and nitride treatment alone produce, lowering metal-to-metal friction between the carrier and upper receiver during cycling and reducing the rate at which carbon fouling adheres to the carrier exterior
- Magnetic Particle Inspection tests each bolt for subsurface cracks, voids, and material defects that visual inspection cannot detect, verifying structural integrity before the bolt leaves the factory and before it enters service in a hard-use rifle
- The S7 tool steel extractor is a higher-impact-resistance alloy than the standard carbon steel extractor found in mil-spec BCGs, providing better resistance to chipping and fracture at the extractor hook under high-volume extraction cycles and with steel-cased ammunition
- The gas key uses grade 8 fasteners torqued and fully staked at both screw heads, preventing the fasteners from backing out under sustained firing and maintaining the gas seal between the key and the carrier that the action depends on for consistent cycling
- Bolt lug chamfering at the back of the lugs reduces the sharp edge that causes carrier tilt-related feeding interruptions in some upper receiver and barrel extension combinations, supporting reliable cycling with modern lightweight triggers and fast-cycling buffer systems
Practical Benefits
- The M16 carrier profile maintains the full-auto trip and works with standard mil-spec, single-stage, two-stage, and drop-in cassette trigger groups without compatibility issues, giving the builder complete freedom in trigger selection
- The Superfinished carrier body runs cleaner and longer between cleaning sessions than a standard mil-spec carrier, a practical advantage during competition matches, training courses, or range sessions where extended operation without cleaning is expected
- The complete assembly ships with extractor spring, insert, and Crane O-ring already installed, giving the builder a ready-to-drop-in BCG that requires no additional small parts to complete the upper receiver assembly
- At 11.4 ounces, this BCG operates within the standard weight range for a mil-spec M16-pattern carrier, pairing correctly with standard carbine and mid-length buffer systems without requiring gas system adjustments on a properly tuned upper
- Whether you are completing a custom AR-15 build on the Ruger stripped lower, replacing a worn factory BCG in a hard-use rifle, or building a dedicated competition or training upper that needs a reliable, low-maintenance bolt carrier group, your Faxon FF556BCGCNITRIDE gives you a domestically made, fully inspected assembly built to run further and clean easier than a standard mil-spec replacement
The Faxon Superfinished 5.56 M16 Bolt Carrier Group (FF556BCGCNITRIDE) is a smart addition for AR builders and hard-use rifle owners who want a 9310 steel, MPI-tested, Superfinished BCG that delivers better material quality, inspection standards, and surface performance than a standard mil-spec replacement.
| MANUFACTURER | FAXON FIREARMS |
| CALIBER | 5.56MM |