CMMG Mk9 9mm Radial Delayed Blowback Parts Kit Colt/ Metalform Mags

Parts Kit for Mk9, 9mm radial delayed blowback. Includes buffer spring, buffer, mag release Mk9, bolt catch Mk9, and feed ramp Colt/Metalform Mag Optimized. CMMG has made a small modification to 9mm barrels to be compatible with Mk9 lower receivers. This modification only applies to Mk9 platform lower receivers and does not positively or negatively affect functionality of the barrel with MkGs, Mk4 or Mk17 platform lower receivers. Barrels stamped “9mm Luger” will be compatible with an upgraded Mk9 lower receiver. If your barrel is marked “9x19 NATO”, you will need to purchase a new 9mm barrel to ensure reliable function.