The AM-15 Optic Ready, 5.56 16″ – M4 is our Entry Level Rifle. With manufacturing all our parts here at Anderson Manufacturing we are able to offer you Affordable, American Made, Quality for Less! The Optic Ready Rifle is a high quality rifle for a low cost. Just add an optic of your choice and you are ready to take on range day! Technical Specifications Lower Receiver Material Forged 7075 T6 Aluminum Lower Receiver Finish Type 3 Hard Anodized - Black Trigger Guard Open Trigger Bolt Carrier Finish Magnesium Phosphate Bolt Carrier Material 8620 Steel Bolt Finish Magnesium Phosphate Bolt Material 9310 Steel Barrel Material 4150 Chrome Moly Vanadium Barrel Length 16 inch Barrel Finish Nitride Barrel Contour M4 Contour Twist Rate 1:8 Gas System Length Carbine Length Gas Block Diameter 0.750 inch Charging Handle Standard Charging Handle Bolt Carrier Group Standard M16 Profile Handguard A2 Plastic Hand Guard Pistol Grip A2 Style Thread Pattern 1/2 - 28 Muzzle Device A2 Flash Hider Buffer Tube 6 Position Buffer Tube Buttstock 6 Position Carbine Buttstock Weight 9.00 Country of Mfg United States RF-85 Treated Non-treated UPC 784672476874