The Mk57 platform, chambered in 5.7x28mm, is our receiver set employs both our Radial Delayed Blowback™ operating system and makes use of FN®* Five-seveN®* pattern magazines.
Virtual Patent Information can be found here.
*FN HERSTAL®, FN®, Five-seveN®, and FN Five-Seven® are registered trademarks of FN Herstal SA Société Anonyme. CMMG® has no affiliation with FN Herstal, and CMMG® products are not approved or endorsed by FN Herstal.