Product Description The Aero Precision APRH308186 Complete .308 Win / 7.62x51mm NATO Black Nitride Bolt Carrier Group (BCG) is a precision-engineered firing mechanism built for the M5 platform and designed for demanding big-bore rifle builds. The carrier is machined from 8620 tool steel and finished in advanced black nitride, which reduces friction, minimizes lubrication requirements, and simplifies maintenance. The gas key is crafted from 4130 steel, secured with grade 8 hardware that is properly staked for lasting reliability. The bolt is case hardened 9310 steel, shot peened, black nitride coated, and features a precision ground external surface along with a reduced firing pin hole diameter for accurate timing. The firing pin is machined from 8740 steel with a high chrome coating. Forward assist serrations provide added functional utility, and laser-engraved Aero Precision branding adds a distinctive finishing touch. Multi-caliber compatibility supports .308 Win, 7.62x51mm NATO, 6.5 Creedmoor, .338 Federal, and other .308-based cartridges. Each BCG undergoes Magnetic Particle Inspection (MPI) and High Pressure Testing (HPT) to ensure dependable performance under the most demanding conditions. The complete kit includes a bolt carrier, complete bolt, firing pin, cam pin, retaining pin, and an Aero Precision "A" logo. Product Highlights Black Nitride Finish: Advanced surface treatment reduces friction, lowers lubrication needs, and makes cleaning significantly easier compared to traditional phosphate finishes. Premium Steel Construction: Carrier machined from 8620 tool steel with a 9310 bolt and 4130 steel gas key, delivering outstanding durability for high-demand rifle applications. MPI and HPT Tested: Every bolt carrier group undergoes Magnetic Particle Inspection and High Pressure Testing to guarantee consistent, reliable performance. Multi-Caliber Compatibility: Designed to function with .308 Win, 7.62x51mm NATO, 6.5 Creedmoor, .338 Federal, and other .308-based cartridges for exceptional versatility. Complete Ready-to-Install Kit: Includes bolt carrier, complete bolt, firing pin, cam pin, retaining pin, and Aero Precision "A" logo for a full drop-in installation experience. Specs Brand: Aero Precision MPN: APRH308186 UPC: 815421020168 Platform: M5 (.308/7.62) Caliber Compatibility: .308 Win, 7.62x51mm NATO, 6.5 Creedmoor, .338 Federal, and other .308-based cartridges Carrier Material: 8620 Tool Steel Bolt Material: 9310 Steel (case hardened, shot peened) Gas Key Material: 4130 Steel Firing Pin Material: 8740 Steel with high chrome coating Finish: Black Nitride Gas Key Hardware: Grade 8, properly staked Testing: MPI (Magnetic Particle Inspection) and HPT (High Pressure Testing) Forward Assist Serrations: Yes Included Components: Bolt carrier, complete bolt, firing pin, cam pin, retaining pin, Aero Precision "A" logo 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. ]]>