Diamond head Model 4 Rifle is our light weight configuration while still offering all of the Diamondhead USA classic features. This rifle is built with a high quality 16 chrome lined barrel protected by our industry leading VRS-T Series free float handguard. This extremely light and solid mounting for-end gives unmatched ergonomics for your hands and the most solid and reliable mounting platform for your Diamondhead Polymer Integrated Sight with NiteBrite photoluminescent inserts in both the front and rear sight. - Action: Semi-Auto Direct Impingement - Caliber: 5.56 NATO - Twist Rate: 1/9 Button Rifled - Handguard: VRS-T 10.25 M-LOK Series 3 - Sights: Diamondhead Polymer Integrated Sighting System w/ NiteBrite photoluminescent inserts - Muzzle Device: A2 Flash hider - Barrel: 16 4150 Steel Chrome Lined Government Profile Manganese Phosphate Coated - Receiver Material: Forged and Mil-Spec 7075 T6 Aluminum with Type 3 Hard Coat Anodizing - Bolt Carrier: Melonite finished 8620 Steel MPI inspected - Gas System: Carbine Length with Low Profile Gas Block - Thread Pitch: 1/2x28TPI - Upper Receiver: Forged and Mil-Spec out of 7075 T6 aluminum with M4 feed ramps. Type III Hard Coat Anodized - Lower Receiver: Forged and Mil-Spec out of 7076 T6 aluminum. Type III Hard Coat Anodized - Buffer: H Buffer - Stock: M4 style 6 position collapsible - Pistol Grip: A2 style - Magazine: 30 rd mil-spec aluminum magazine (to all states where legal) - Case: Full size hard case with locking latches.