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.
- 5.7×28 to 22lr Conversion Chamber Adapter
- Stainless Steel Construction
- Compatible with all CMMG Mk57 Uppers
- Simple Installation — No Tools Required
**Not compatible with Mk57 Lower Groups or 5.56/.223 uppers**