This Rosco 10.3" SOCOM 5.56 NATO Bloodline Barrel is designed to be the perfect addition to any SBR or Pistol build. ALL NFA RULES APPLY!Almost identical to our beloved Bloodline barrel, the main exception being the thicker SOCOM profile and 10.3" length. Barrel Length 10.3" Barrel Weight 24 Oz Barrel Material 4150 CMV Barrel Caliber 5.56 Barrel Profile SOCOM Twist 1/7 Barrel Thread 1/2 x 28 Gas Block Size .750 Gas System Length Carbine Barrel Finish Nitride Barrel Extension Finish Nitride