LANTAC AR15 Raven .223 WYLDE 556NATO 18 Inch 1/2-28 .750 Dia Gas Block Match Grade Cryo Treated Barrel Black LAN. Each barrel is chambered and head spaced to a master bolt face with barrel extension individually matched to each barrel too. Chambers are carefully polished after reaming. Our barrel blanks are precision gun drilled double reamed precision honed and then rifled with a progressive button system utilizing 6 groove rifling that has been proven to produce the highest level of shooting accuracy. Barrels are also air gauged with a bore concentricity tolerance between .00005''to .0001'' and Cryogenically treated. All muzzles are precision 11 target crowned. Specifications for LANTAC AR15 Raven .223 WYLDE 556NATO 18 Inch 1:7 1/2-28 .750 Dia Gas Block Match Grade Cryo Treated Barrel: Manufacturer: LANTAC Color: Black Features of LANTAC AR15 Raven .223 WYLDE 556NATO 18 Inch 1:7 1/2-28 .750 Dia Gas Block Match Grade Cryo Treated Barrel: Certified 416R Stainless Steel Highest 'Barrel Quality' steel available cryogenically treated and double stress relieved. 1:7 Twist Rate. Ultra precise 6 groove 2 pass button process proven to perform to the highest levels of accuracy. Head-spaced to master bolt face. Extended M4 feed ramps YAG Fiber laser engraved logos and nomenclature. Fine bead blasted finish before final surface treatment Proprietary black surface conversion finish 1/228 muzzle threads with precision 11 target crown Lantac USA barrel contour Package Contents: LANTAC AR15 Raven .223 WYLDE 556NATO 18 Inch 1:7 1/2-28 .750 Dia Gas Block Match Grade Cryo Treated Barrel LANTAC LANLA00236: AR15 Raven .223 WYLDE 556NATO 18 Inch 1/2-28 .750 Dia Gas Block Match Grade Cryo Treated Barrel Black