Rosco's Bloodline 16" 5.56 Heavy Barrel: This Rosco 16" 5.56 Heavy Barrel (HB) was made to cater to end users who need to run their guns hard without any remorse. The heavy contour barrel is well suited for full auto use and abuse.Our Rosco 5.56 (NATO) barrels are designed to meet the modern day carbine shooters requirements. We are a long way from our daddy's "Sporter" AR, and those specs just won't cut it anymore. From properly managed dwell times for SBR's, to running Suppressed, or setting up a balanced patrol carbine we have incorporated your needs into our engineering. We have successfully accomplished this by picking the right twist rates, gas port diameters, and barrel materials according to the barrel we are making (not a lazy blanket method). We have also balanced input from our consumers and military end users in order to bring you the rifle barrel you need, not just the one we want to sell you. Barrel Length 16" Barrel Weight 35.76 Oz Barrel Material 4150 CMV Barrel Caliber 5.56 Barrel Profile Heavy Twist 1/7 Barrel Thread 1/2 x 28 Gas Block Size .750 Gas System Length Carbine Barrel Crown 11 Degree Barrel Finish Nitride Barrel Extension Finish Nitride Browse all of our 5.56 NATO Bloodline Barrels >>