This Rosco 5.56 NATO Bloodline Barrel is designed to be the perfect addition to any SBR or Pistol build. From properly managed dwell times for SBR's, to running Suppressed, or setting up a balanced patrol carbine Rosco has incorporated your needs into their engineering. They have successfully accomplished this by picking the right twist rates, gas port diameters, and barrel materials according to the barrel that is being made. All NFA rules apply Features11 Degree barrel crownNitride Barrel and barrel extension4150 CMV materials