PRODUCT WEIGHT 6 lb 2 ozCALIBER 5.56x45mm NATO Can fire both .223 or 5.56mmOPERATION SYSTEM Direct Gas ImpingementBARREL LENGTH 16"BARREL TYPE Heavy BarrelTWIST RATE 1:9BARREL MATERIAL 4140 Chrome MolyBARREL FEATURES M4 FeedrampsSIGHT / GAS BLOCK "F" Marked Front SightMUZZLE DEVICE A2 Flash HiderHANDGUARD Polymer 2-Piece (CAR Length)UPPER RECEIVER TYPE FlattopUPPER RECEIVER MATERIAL Forged Aircraft 7075 T6 AluminumUPPER RECEIVER COATING Anodized to Mil-Spec