Noveske is proud to manufacture premium barrels for all types of builds. This barrel ships with gas block. This barrel is designed for the Noveske gas block that is 1" long (INCLUDED). A standard front sight base is 1.9" long and WILL NOT FIT. Barrel installation should be performed by a qualified gunsmith. Installation of the gas block dowel pin and gas block is required to complete the assembly process.Features :"1 in 7" twist improved polygonal rifling with 556 Noveske Match Chamber,Extended feed rampsBead blasted finishGas tubePinned Low Profile Gas Block, .750"1/2x28 threads--aside from the 20";"Medium Contour,