A .308 bolt carrier group (BCG) is a critical component for AR-10 rifles chambered in .308 Winchester or 7.62×51 NATO. It includes the bolt, carrier, gas key, firing pin, cam pin, and retaining pin. The .308 BCG works with AR-10 upper receivers, .308/7.62 barrels, charging handles, and lower receivers. It ensures reliable cycling, chambering, extraction, and firing, making it essential for building or upgrading AR-10 platforms in .308/7.62 calibers.