CMMG Replacement Barrel Kit with Bolt Carrier Group, 22 LR 4.50" Threaded, Black Nitride Chromoly Steel, Fits AR-15/Mk4 22D5B6E

In this Barrel and Bolt Group Kit, CMMG provides everything you need to convert your AR-15 into a dedicated .22 LR rimfire training platform.

The barrel measures 4.5 inches long and is machined from 4140 chrome-moly steel, complete with a salt-bath nitride finish and a medium-taper profile. The barrel is optimized with a 1:16-inch twist that's compatible with most .22 LR bullets on the market, but the system runs best with 36-grain round-nose bullets.

Each .22 LR Barrel and Bolt Group Kit from CMMG also features a .22 LR sporting chamber, as well as a threaded muzzle measuring 1/2-28 TPI thread pitch. CMMG recommends using a round-style hammer in place of a notched hammer to avoid function issues. The only other piece of the kit needed for a functioning system is a dedicated .22 LR magazine.