Starts with Luth-AR's 14.5a ^2 M4 SOCOM profile barrel with F Marked Front Sight Base, 5.56mm, made from 4150 CMV steel with a 1-7a ^2 twist mated to the A3 Flattop receiver which includes their bolt carrier, charging handle, forward assist and ejection port cover. Upper Specs: 7075-T6 Forging Hard coat anodize Black Bolt Specs: Bolt: Carpenter 158 steel Extractor: 4140 Alloy steel Army Spec Heat Treatment Manganese Phosphate Bolt Carrier Specs: Carrier: 8620 steel Cam pin: 4340 Alloy steel Carrier key: 4130 Alloy steel Army Spec Heat Treatment Manganese Phosphate Barrel Specs: Mfg: Luth-Ar