Purebred 10.5" 300 Blackout Barrel: This Rosco Purebred 10.5" 300 Blackout Barrel was designed for SBR/ Pistol use in conjunction with suppressors. The 10.5" Rosco barrel was made to be a direct precision replacement for any MK 18 platforms that are currently in 5.56 NATO. The 10.5" barrel is also perfect for carbines which require a slightly longer rail in order to run PEQ-15s" D-BAL (series), or any laser aiming devices comfortably. ALL NFA RULES APPLY! Rosco Manufacturings Purebred series is a testament to precision and quality manufacturing. Rosco took a step back to see how Rosco could create a barrel line that would be a culmination of all the lessons learned through years of making barrels for several OEMs. The result is a barrel that will produce results out of the box for any shooter that is looking to take their skills above and beyond.Features :,Barrel Length: 10.5";"Barrel Weight: 21.09 oz,Barrel Material: 416 RBarrel Caliber: 300 BLKBarrel Profile: HeavyTwist: 1/7Barrel Thread: 5/8 x 24Gas Block Size: .750Gas System Length: PistolBarrel Crown: Step Crown