CMMG 57AFF37 Mk57 Bolt Maintenance Parts Kit

Replacement firing pin, retaining pin, and cam pin for Mk57 firearms.

Replacement firing pin, retaining pin, and cam pin for Mk47 firearms.

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...

The personal defense caliber SBR hunt is over. Chambered in one of the most popular PDW cartridges, 5.7x28mm, the Mk57 SBR features an 8'' barrel to better extract the full ballistic performance...

Parts kit, AR15, Bolt Catch