DPMS DP51655152558: Details - Barrel Length: 16 - Barrel Material: 4150V Chrome Moly Vanadium Steel - Barrel Finish: Phosphate - Barrel Profile: M4 - Chamber: 5.56 NATO - Twist Rate: 1 in 7 - Extension: M4 - Gas System: Carbine-Length - Gas Block Type: Low Profile .750 Diameter - Upper Receiver: Forged 7075 T6 Aluminum - Receiver Style: M4 Flat top with feed ramps - Receiver Finish: Hardcoat Anodized - Forward Assist: No - Dust Cover: No - Handguard Style: DPMS M-Lok Free Float Rail - Bolt Steel: Carpenter 158 Mag Phosphate coated - Bolt Carrier Steel: 8620 Chrome Lined - Staked Gas Key: Yes - Lower Receiver: Forged 7075 T6 Aluminum - Receiver Finish: Hardcoat Anodized - Fire Control Group: AR-15 Mil-Spec Fire Control Group - Buffer Tube: 7075 T6 Aluminum Mil-Spec Tube - Adjustment: 6-position collapsible - Stock: Classic Carbine Stock - Magazine: (1) 30-Round Magazine (where available by law) - Weight: 7 Lbs - Length: 32