CMMG Buffer Assembly, MK3 AR-10, Carbine, Silver 38CA929 CMMG'S 308 AR Carbine Buffer Assembly can be used in conjunction with the CMMG 308 carbine buffer spring in AR-15 buffer tubes. Compatible with LR-308 Mk3 and AR-10's. All CMMG parts are made in the United States from the best materials available. CMMG guarantees its products against defects in material or workmanship for the life of the product.