Specifications: Barrel Material: 416-R Barrel Type: 5R Button Rifled Barrel Caliber: .308 WIN Barrel Twist: 1:10 Barrel Length: 18 Barrel Profile: Heavy Fluted Barrel Gas System: Rifle (1.1 Journal) Inside Finish: Salt Bath Nitride Outside Finish: Salt Bath Nitride Muzzle Thread: 5/8-24 TPI Gas Block Diameter: .750 Gas Block Journal Length: 1.1 Barrel Extension: DPMS LR-308 Compatible - Nickel Teflon Coated Barrel Weight: 2.25 Lbs Magnetic Particle Inspected! 11-degree Polished Target CrownNote:Faxon Firearms barrels are chambered to SAAMI specification .308 Winchester at a nominal headspace depth (passing Go and failing No-Go). This ensures maximum safety and accuracy.7.62x51 NATO is not the same round as .308 Winchester, though it will fit within chamber. 7.62x51 technically requires deeper headspacing to meet the military specification and is known to function in Faxon .308 WIN barrels under most circumstances. However, due to the variation of components in the .308 AR world and variations between loadings, Faxon cannot guarantee or warrant function with 7.62x51, especially with bolts with tight (match) .308 WIN headspacing.