F Diamondback Firearms OEM Replacement Barrel, FN Herstal, M16, 5.56x45mm NATO, 5.5in, Heavy Profile, Pistol-Length, 1-8 Twist, 1/2 x 28 Thread, 4150 CrMov, Black Nitride, 556P55H50B8R $69.99 556P55H50B8R show more like this Dvor