Product Description The Rosco Manufacturing 5.56 NATO / 300 Blackout bolt carrier group (BCG) is built to meet modern AR-15 carbine demands with a durable phosphate-coated finish and chrome-lined gas key and bolt channel for extended service life. Full-auto rated and built to MIL specifications, it features a properly staked gas key and a matched, shot-peened bolt that is magnetic particle inspected (MPI) and high-pressure tested (HPT) for dependable performance under hard use. Each component is selected for strength and longevity, helping deliver consistent cycling and reliable operation. Product Highlights Phosphate-coated BCG with chrome-lined gas key and bolt channel for enhanced durability Full-auto rated, MIL-spec build with properly staked gas key for reliable cycling Shot-peened, matched bolt that is MPI and HPT tested for proven strength Premium steel construction throughout (8620 carrier, C158 bolt, 4130 gas key, 4340 cam pin) Ships with upgraded Sprinco extractor kit for improved extraction performance Specs Brand: Rosco Manufacturing Product Type: Bolt Carrier Group (BCG) Compatibility: 5.56 NATO / 300 Blackout Finish/Coating: Phosphate coated; chrome-lined gas key and bolt channel Carrier Material: 8620 steel Gas Key Material: 4130 steel; Grade 8 hardware; properly staked Cam Pin Material: Hardened 4340 steel Firing Pin: 8740 steel; heat treated; mil-spec; center-less ground; hard chrome plated Bolt Material: C158; phosphate coated; MPI/HPT Extractor: 4140 steel; heat treated; shot peened Ejector: S2-S7 tool steel; shot peened Included: Upgraded Sprinco extractor kit UPC: 850039693113 Manufacturer Part Number: ROS-BCG-002 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.