Product Description The Aero Precision M5 Complete Bolt Carrier Group (BCG) is a premium firing mechanism purpose-built for big-bore AR-platform rifle builds chambered in .308 Win, 7.62x51mm NATO, 6.5 Creedmoor, .338 Federal, and other .308-based cartridges. The carrier is machined from 8620 Tool Steel and features a mil-spec Black Phosphate finish, forward assist serrations, and a laser-engraved Aero Precision "A" logo. The gas key is constructed from 4130 Steel, attached with Grade 8 hardware, and properly staked to ensure reliable function. The firing pin is machined from 8740 steel and hard chrome coated for long-lasting durability. The complete bolt is case-hardened 9310 Steel, Magnetic Particle Inspected (MPI) and High Pressure Tested (HPT), and features double o-rings and double springs on the extractor -- machined from 4340 Steel -- for enhanced reliability. This BCG is fully compatible with AR .308/M5-compatible upper receivers and rifles, and arrives complete right out of the box. Product Highlights Multi-Caliber Compatibility: Designed to function with .308 Win, 7.62x51mm NATO, 6.5 Creedmoor, .338 Federal, and other .308-based cartridges for maximum versatility. Premium Steel Construction: Carrier machined from 8620 Tool Steel; bolt case-hardened from 9310 Steel for exceptional strength and durability. Mil-Spec Black Phosphate Finish: Provides reliable corrosion resistance and long-term performance in demanding conditions. MPI and HPT Tested Bolt: Magnetic Particle Inspected and High Pressure Tested for verified quality, featuring double o-rings and double springs on the 4340 Steel extractor. Complete Ready-to-Install Kit: Includes bolt carrier, complete bolt, firing pin, cam pin, retaining pin, and laser-engraved Aero Precision "A" logo for a hassle-free build. Specs Brand: Aero Precision MPN: APRH308184 UPC: 815421020144 Caliber: .308 Win / 7.62x51mm NATO / 6.5 Creedmoor / .338 Federal / Other .308-Based Cartridges Platform: AR-308 / M5 Carrier Material: 8620 Tool Steel Bolt Material: Case-Hardened 9310 Steel Gas Key Material: 4130 Steel with Grade 8 Hardware, Properly Staked Firing Pin Material: 8740 Steel, Hard Chrome Coated Extractor Material: 4340 Steel with Double O-Rings and Double Springs Finish: Black Phosphate Color: Black Carrier Type: M16 Weight: 1.16 lbs (18.56 oz) Includes: Bolt Carrier, Complete Bolt, Firing Pin, Cam Pin, Retaining Pin Country of Manufacture: USA 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. ]]>