22ARC Mk57 Chamber Adapter Assembly

Easily convert your CMMG 5.7x28mm Upper Receiver Group into a .22LR in seconds! The new Mk57 .22LR Conversion Kit is simple to use. Just remove the existing CMMG bolt carrier group from your 5.7—28 upper and replace it with the drop-in conversion. Pair the upper with any Mil-Spec AR15/Mk4 lower receiver and then use the included magazine to safely shoot .22LR. It's a great way to get in more trigger time while saving money on ammo. This conversion kit is designed for use with all CMMG Mk57 5.7x28mm upper receiver groups and bolt/barrel combinations when paired with an AR15 Lower.