Product Description The Faxon Firearms Superfinished 5.56 M16 Bolt Carrier Group (BCG) is a high-performance upgrade built to deliver smooth cycling, reliable extraction, and long service life in AR-15/M16-pattern rifles chambered in 5.56x45mm NATO. This M16-pattern, full-auto compatible BCG features a 9310 tool steel bolt and a salt bath nitride treatment on the bolt and carrier to enhance surface hardness and corrosion resistance. Faxon&';s Superfinished carrier body helps reduce friction and fouling for easier maintenance and consistent operation under hard use. Key durability features include MPI-tested bolt construction, chamfered bolt lugs for reliable cycling, a properly staked gas key with grade 8 fasteners, and an S7 extractor with spring/insert and "Crane" O-ring installed. Product Highlights Superfinished carrier body helps reduce friction and carbon buildup for smoother AR-15/M16 cycling Salt bath nitride-treated bolt and carrier for increased hardness and corrosion resistance 9310 tool steel bolt with Magnetic Particle Inspection (MPI) testing for added confidence M16-pattern, full-auto compatible design with forward assist serrations Grade 8 gas key fasteners with full staking, plus S7 extractor and "Crane" O-ring installed Specs Product Type: Bolt Carrier Group (BCG), M16 pattern Platform Compatibility: AR-15 / M16 pattern rifles Caliber Compatibility: 5.56x45mm NATO Bolt Material: 9310 tool steel Finish / Treatment: Salt bath nitride (bolt & carrier); Superfinished carrier body Inspection: MPI tested bolt Gas Key: Grade 8 fasteners; fully staked Extractor: S7 extractor; spring/insert and "Crane" O-ring installed UPC: 816341020870 Manufacturer Part Number: FF556BCGCNITRIDE Brand: Faxon Firearms Disclaimer: We strive to provide accurate and up-to-date product descriptions, specifications, and images; however, errors or omissions may occasionally occur. We are not responsible for any inaccuracies or discrepancies in the content provided. If you notice anything incorrect or unclear, please contact us so we can correct it. When in doubt, we recommend verifying details directly with the product&';s manufacturer.