CMMG 22D5B6E Replacement Barrel Kit with Bolt Carrier Group, 22 LR 4.50" Threaded, Black Nitride Chromoly Steel, Fits AR-15/Mk4
Everything you need to convert your existing upper to a dedicated .22LR. Just purchase a magazine and you are ready to go. For best performance use a round style hammer as notched hammers can cause function issues and 36 grain plated nose bullets have proven to be the best choice for function.