Rosco Manufacturing 10.5" M4 5.56 NATO Barrel Rosco Manufacturing 10.5" M4 5.56 NATO Barrel Bloodline 10.5″ M4 5.56 NATO: This Rosco 10.5″ M4 5.56 NATO Bloodline Barrel is designed to be the perfect addition to any SBR or Pistol... MSRP: Was: Now: $139.99 Add to Cart