Bloodline 5.5″ 9mm Barrel: This Rosco 5.5″ 9mm Barrel was primarily designed for suppressed carbines/ pistols where the handguard will be ran over the rail. It will give you the flexibility of running a suppressed platform that offers the most compact size possible without sacrificing performance. Twist rates have also been taken into account in order to optimize performance for a multitude of rounds that you may also be running out of your duty/ concealed carry pistol in order to allow a “cross platform” ballistic familiarity. ALL NFA RULES APPY!