CMMG Replacement Barrel Kit Features The CMMG Replacement Barrel Kit centers on a 16.1 inch .22 LR barrel built from 4140 chromoly steel chosen for its strength and resistance to the heat generated during extended shooting sessions. The salt bath nitride finish is applied both inside and outside the bore protecting against corrosion while also improving the surface hardness that affects long-term accuracy. An M4 profile keeps the barrel s exterior contour consistent with standard AR-15 handguard fitment so it drops into common furniture without modification. The 1:16 twist rate is matched specifically to .22 LR sporting ammunition giving reliable stabilization across typical bullet weights used in rimfire conversions. A 1/2x28 threaded muzzle allows the installation of a suppressor or muzzle device which is especially useful on a .22 LR platform often run suppressed for reduced report. The kit includes a barrel collar which replaces the chamber adapter used on a 22LR AR-15 conversion simplifying the swap to a dedicated rimfire upper. This barrel is intended for AR-15 and Mk4 platforms letting builders put together a purpose-built .22 LR upper group rather than relying on a conversion kit alone. Combined with its chromoly construction and protective finish the CMMG Replacement Barrel Kit is a durable foundation for a dedicated rimfire training or plinking rifle. CMMG Replacement Barrel Kit Specifications Manufacturer: CMMG Model: Replacement Barrel Kit Caliber: .22 LR Compatible Hosts: AR-15 Mk4 Color: Black Material: 4140 Chromoly Steel Finish: Salt Bath Nitride Twist Rate: 1:16 Barrel Length: 16.1 Thread Pattern: 1/2x28 Includes: Collar Available At: GrabAGun