CMMG Mk4 K AR Pistol 5.56mm
CMMG Adds 5.56mm Version to Mk4 K AR Pistol Lineup

CMMG’s Mk4 K AR Pistol family just got a big boost … with a bigger barrel.

The firearms manufacturer has announced that it will add a 5.56mm version to its recently released lineup of AR pistols.

Aside from the caliber, the most notable difference in this new Mk4 K AR Pistol in 5.56mm is that it features a 12.5-inch barrel, compared to the 8.2-inch barrel found on the .300 AAC Blackout and 9mm versions. The increased barrel length will help with accuracy when using the popular 5.56mm cartridge.

The Mk4 K AR Pistol comes with a Magpul MOE pistol grip and stock, an A2 muzzle compensator and features an ambidextrous rear sling mount.

It also has a slim, ergonomic profile, thanks to CMMG’s RKM11 free-floating KeyMod hand guard. The KeyMod slots are located at the 3, 6 and 9 o’clock positions and allow users to mount compatible accessories directly to the hand guard.

For accessories that are not yet compatible with the KeyMod system, CMMG offers separate five-slot rails that attach to the hand guard. For mounting sights or optics, a 1913 Picatinny rail runs across the top of the firearm.

The Mk4 K AR Pistol in 5.56mm retails for $1,049.95.

For more information on the newest addition to the Mk4 K AR Pistol family, please visit

CMMG AR Pistol Specifications:
Caliber:  5.56mm
Barrel:  12.5″ medium weight, 1:7” twist
Muzzle:  A2 Compensator
Hand Guard:  CMMG RKM11 Free-Float KeyMod hand guard
Receiver:  Forged 7075-T6 AL
Trigger:  Single Stage Mil-Spec Type
Furniture:  Magpul MOE Pistol Grip
Weight: 5.3 lbs unloaded
Length: 28 inches
Magazine:  30-round PMAG

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