CMMG 5.56mm Non-Threaded Barrel 16.1in Empire Profile 55D 4140CM SBN Sub-Assm Black. 1" Empire Profile barrel sub-assembly is engineered for 5.56mm featuring a medium-taper design crafted from 4140 Chrome-Moly steel with a durable Salt Bath Nitride (SBN) finish. The barrel incorporates an unthreaded muzzle with a recessed target crown. This configuration was specifically developed to provide a reliable option for areas with specific firearm regulations while maintaining CMMG's standards for accuracy and durability. Specifications for CMMG 5.56mm Non-Threaded Barrel: Manufacturer: CMMG Color: Black Finish: Anodized Caliber: 5.56mm Barrel Length: 16.1 in Barrel Material: 4140 Chrome Moly Vanadium Gun Make: CMMG Gun Model: CMMG Mk4 Threads per Inch: Non Threaded Features of CMMG 5.56mm Non-Threaded Barrel 16.1" barrel length 5.56mm chambering 4140CM steel construction Salt Bath Nitride finish Unthreaded muzzle design Recessed target crown Medium taper Empire Profile Package Contents: CMMG 5.56mm Non-Threaded Barrel What firearm models does the manufacturer say CMMG 5.56mm Non-Threaded Barrel is compatible with? The manufacturer says that CMMG 5.56mm Non-Threaded Barrel is compatible with CMMG Mk4CMMG 55DF40B: 5.56mm Non-Threaded Barrel 16.1in Empire Profile 55D 4140CM SBN Sub-Assm Black