Noveske Lo-Pro Gas Block 5.56 Barrel 13.7in Infidel Mid Length Stainless .750 Gas Block Gtml Headspaced Bolt 0. This barrel is designed for our 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. All NFA Regulations apply. Please check your local and state laws before ordering. Contact your local ATF Field Office with any NFA questions you may have. Specifications for Noveske Lo-Pro Gas Block 5.56 Barrel: Manufacturer: Noveske Color: Stainless Fabric/Material: Stainless Steel Caliber: 5.56x45mm NATO Threads per Inch: 1/2x28 Barrel Twist Rate: 1-7 Additional Features: Medium Contour .750 Gas Block Condition: New Package Contents: Noveske Lo-Pro Gas Block 5.56 Barrel The Noveske Lo-Pro Gas Block 5.56 Barrel is a quality addition to the Noveske lineup. For more great deals on AR15 Barrels by Noveske please browse our Noveske Gun Parts page. Noveske 07000071: Lo-Pro Gas Block 5.56 Barrel 13.7in Infidel Mid Length Stainless .750 Gas Block Gtml Headspaced Bolt