CMMG Parts Kit, Mk9, 9mm Radial Delayed Blowback

CMMG Parts Kit, Mk9, 9mm Radial Delayed Blowback™, Colt/ Metalform Mags Parts Kit, Mk9, 9mm Radial Delayed Blowback™, Colt/ Metalform Mags BUFFER SPRING: Carbine BUFFER: Carbine MAG RELEASE: Mk9 BOLT CATCH: Mk9 FEED RAMP: Colt/Metalform Mag Optimized CMMG has made a small modification to 9mm barrels in order for them 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 a MkGs, Mk4 or Mk17 platform lower receiver. Barrels that are 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 in order to ensure reliable function.