Rosco's 5.56x45mm and .300 AAC Blackout Bolt Carrier Groups are engineered for durability, reliability, and peak performance. These full-auto-rated BCGs feature a Melonite coating that enhances wear resistance and corrosion protection, ensuring long-term functionality under harsh conditions. Each unit is built to MIL-SPEC standards, with a properly staked gas key for secure operation and a matched bolt that undergoes shot peening and magnetic particle testing for superior strength. Designed to lock up precisely with Rosco barrel extensions, these BCGs deliver exceptional accuracy and consistency. The upgraded extractor enhances reliability, while the rugged construction withstands the demands of full-auto fire and rigorous use. Developed with input from both consumers and military end users, these bolt carrier groups are built to exceed expectations and meet the needs of modern carbine shooters. Be sure to check local laws and regulations regarding ownership. The 8620 steel carrier ensures strength and reliability under heavy use The 4130 steel construction is attached with grade 8 hardware and features a properly staked gas key for reliability Hardened 4340 cam pin, providing enhanced strength and durability for critical firearm components The 8740 steel firing pin is Mil-Spec, centerless ground and hard chrome-coated for improved performance and longevity The 9310 bolt material is properly heat-treated, MPI/HPT tested and ensures exceptional durability The 4340 steel extractor offers exceptional strength and durability for reliable performance Features an S7 tool steel ejector for superior strength and reliability