KAK Industry's rugged and dependable .224 Valkyrie/6.8 SPC bolt carrier group features a chrome lined interior and phosphate finish. As the workhorse of KAK Industry's BCG lineup, it is designed to deliver years of reliable performance without the high-price tag. M16 auto profile carrier machined from aircraft and bearing quality 8620 steel, properly heat-treated, precision ground and finished with a chrome-lined phosphate coating for durability and corrosion-resistance Bolt machined from a 1-piece of aircraft/bearing quality 9310 steel, properly heat-treated, precision ground, shot-peened, MPI tested and finished with a phosphate coating for enhanced durability and reliability Firing pin machined to Mil-Spec print from 8740 steel, precision ground and chrome-plated for durability and corrosion-resistance 1-piece billet, fully machined enhanced extractor with a phosphate coating for increased reliability and corrosion-resistance Phosphate-coated cam pin S7 tool steel ejector and extractor retaining pin for enhanced strength and durability 4130 steel gas key, phosphate-coated, precision staked using a hydraulic staking machine and finished with a chrome-lined phosphate coating for enhanced durability and corrosion-resistance KAK carrier key screws with T25 drive, grade 8 and proper heat treatment for durability and secure fastening