Juan,This rifle has a 16" 4140 Chrome-Moly Free Float Barrel with 1:8 Twist Rate

it has a 1:8 right hand twist rate see ******Model: DB15EMLB (Elite Black)
Caliber: 5.56 NATO/ .223 Remington
Finish: Black Anodized Hardcoat
Barrel: Diamondback Barrels 16”, Carbine-Length, Medium, 4150 CrMov, Black Nitride Finish
Twist Rate: 1:8 RH
Gas System: Carbine Length Gas System
Bolt Carrier: Shot-Peened, Magnetic Particle Inspected Mil Spec 8620 carrier
Lower Receiver: Forged 7075 T-6 Aluminum
Upper Receiver: A3 Flattop Forged 7075 T-6 Aluminum, T-Marked
Handguard: 15″ M-LOK Rail
Enhanced Trigger Guard
Pistol Grip: Hexmag Grip
Stock: Adaptive Tactical EX Buttstock
Mag: Magpul P-Mag 30 Round Mag with Window
Overall Length (Stock Collapsed): 32.5”
Overall Length (Stock Expanded): 36.25”
Muzzle Brake: DB 556 Muzzle Brake threaded 1/2 x 28