CMMG Barrel & Bolt Group Kit 4.5" .22 LR 4140 Chrome Moly 1:16 Twist - AR-15 Conversion

Convert your existing AR-15 upper into a dedicated .22 LR rimfire platform with the CMMG Barrel & Bolt Group Kit. This matched 4.5" medium taper barrel and rimfire bolt group is purpose-built for cost-effective rimfire training, plinking, and small-game hunting on your existing MSR upper without the cost and noise of a 5.56 round.

The barrel is precision-machined from 4140 Chrome Moly steel and finished with a salt bath nitride treatment inside and out for excellent corrosion resistance, lubricity, and easy cleanup. It carries a 1:16 twist rate optimized for high-velocity and bulk .22 LR ammunition, a .22 LR sporting chamber for reliable cycling, and a 1/2x28 thread pitch that accepts any standard AR-15 muzzle device or suppressor.

The included rimfire bolt group is engineered specifically for .22 LR function, dropping into a compatible CMMG Mk4 / AR-15 upper in place of the standard 5.56 bolt. This kit is the heart of any CMMG .22 LR conversion, giving you a quiet, low-recoil rimfire option on a familiar platform. Barrel and bolt only - upper receiver, handguard, and other components sold separately.