Caliber: 5.56 NATO. Capacity: 30. Short-stroke gas-piston operating system. One-piece 174 stainless piston. Monolithic TB41 DLC coated anti-tilt full-auto bolt carrier. Forged upper and lower receivers, hardcoat anodized and finished in Cerakote. M4 feed ramps, lightweight free-float handguard. Full-length M1913 Picatinny top rail with Magpul M-LOK accessory mounting slots at 3, 6, and 9 o'clock positions. 7.2 lbs. DI has lengthened gas system. Magpul furniture. Custom Radian Raptor ambidextrous charging handle; extended slimline Barrett handguard, Sides and bottom have Barrett Rail System positions. Subtract 40% for the 16” direct-impingement (DI) variant.