KAK Industry Bolt Carrier Group Features The KAK Industry Bolt Carrier Group is built around an M16 full-auto profile carrier machined from 8620 steel properly heat treated and ground to exact tolerances for smooth reliable cycling in .224 Valkyrie and 6.8 SPC rifles. The bolt itself is machined from 9310 steel a tougher alloy chosen specifically to handle the elevated pressures these cartridges can generate compared to standard 5.56. Chrome lining on the carrier interior reduces friction and fouling buildup extending the interval between cleanings and keeping the action running reliably even under sustained fire. A manganese phosphate finish throughout adds a further layer of corrosion resistance for long-term durability in varied conditions. Supporting components are built to the same standard including a single-piece billet-machined 4140 extractor that is phosphate coated for increased reliability and corrosion resistance over a stamped alternative. An 8740 chrome-plated firing pin precision ground and heat treated pairs with an S7 tool steel ejector and extractor retaining pin for components that will not wear prematurely. The 4130 steel gas key is phosphate coated chrome lined and precision staked addressing one of the most common failure points on lower-quality BCGs. For AR-15 and M16 platform owners building a reliable .224 Valkyrie or 6.8 SPC rifle this bolt carrier group delivers a complete properly engineered solution without the premium price tag of boutique options. KAK Industry Bolt Carrier Group Specifications Manufacturer: KAK Industry Model: Bolt Carrier Group Compatible Hosts: AR-15 M16 Caliber: .224 Valkyrie / 6.8 SPC Color: Black Material: Steel Finish: Manganese Phosphate Carrier Type: M16 Weight: 0.73 lbs Length: 7.125 Available At: GrabAGun