CMMG DISSENT MK4 Pistol .300 AAC Blackout 10.5″ 30+1

About this product

The CMMG DISSENT MK4 Pistol .300 AAC Blackout is a short-barreled, buffer-tube-free AR-platform firearm designed specifically to maximize the terminal ballistics and suppressor compatibility of the .300 Blackout cartridge. It utilizes a patented radial delayed blowback system instead of the conventional direct impingement operating mechanism, providing improved reliability across diverse ammunition types while maintaining a folding-brace-ready profile. This configuration bridges the performance gap between standard AR pistols and purpose-built personal defense weapons, particularly for users operating under the constraints of National Firearms Act regulations regarding short-barreled rifles.

What is the CMMG DISSENT MK4 Pistol .300 AAC Blackout used for?

The primary application is as a compact, high-capacity personal defense weapon optimized for use with a sound suppressor. Its 10.5-inch barrel and adjustable gas block ensure reliable cycling with both 220-grain subsonic and 110-grain supersonic .300 Blackout loads, making it ideal for home defense, vehicle-based security details, or as a discrete patrol carbine for law enforcement. The platform's 18.7-inch overall length with the stock folded allows for rapid deployment from confined spaces like a vehicle cab or a tactical pack, while the 30-round magazine capacity provides substantial firepower without the bulk of a 16-inch rifle.

How does the CMMG DISSENT MK4 Pistol compare to a traditional AR pistol in .300 Blackout?

The DISSENT MK4 outperforms a standard AR-15 pistol like the Springfield Armory Saint Victor in suppressed reliability and compact storage, but requires a more specialized maintenance understanding. Its radial delayed blowback system, operating at a cyclic rate approximately 15% slower than a direct impingement system, generates less port gas and runs noticeably cleaner when shooting suppressed, a critical advantage for high-round-count training sessions. However, unlike the straightforward field-stripping of the Stevens 334 bolt-action rifle, the DISSENT's proprietary bolt carrier group and left-side charging handle present a steeper learning curve for armorers accustomed to mil-spec AR-15 components.

What does it weigh and what are the dimensions?

Unloaded with an empty magazine, the pistol weighs 5 pounds 14 ounces (94.8 ounces), and measures 26.5 inches from the end of the muzzle threads to the back of the 1913 Picatinny rail adapter with an SB Tactical SBA3 brace installed. The handguard is a 9.6-inch M-LOK unit with a 1.5-inch internal diameter, providing adequate clearance for most 1.375-inch-diameter suppressors without needing a rail-mounted adapter. Stowed in a 28-inch Pelican Vault case, the folded configuration reduces its storage length to just under 21 inches, which is 7 inches shorter than a comparable AR pistol with an extended buffer tube.

Who is this NOT for?

This pistol is a poor choice for a first-time firearm owner or someone seeking a low-cost plinking rifle. Its $1,820.99 price point, specialized .300 Blackout chambering (with ammo costing over $1.00 per round for quality subsonic loads), and NFA-compliance considerations for adding a vertical foregrip or stock create multiple barriers to casual use. Buyers who primarily shoot unsuppressed 5.56mm ammunition would be better served by a more conventionally priced 16-inch rifle or a Stevens 334 in .243 Win for hunting applications, as the DISSENT's key advantages are only fully realized with a dedicated suppressor and appropriate ammunition.

What's in the box?

CMMG ships the DISSENT MK4 with the complete pistol, one 30-round CMMG-branded aluminum magazine, the 1913 Picatinny rail end plate adapter, a left-side ambidextrous charging handle, a Toolcraft-dimension bolt carrier group specific to the radial delayed system, and the owner's manual detailing the gas block adjustment procedures. Notably absent are any iron sights, a pistol stabilizing brace, or a case, requiring an additional investment of $150 to $400 for a minimally operational setup. The TriggerTech AR-D trigger is pre-installed and features a 4.0-pound pull weight with a crisp, single-stage break right out of the box.

Is the CMMG DISSENT MK4 Pistol worth it at $1820.99?

Yes, but only for the specific user who requires a maximally compact, suppressor-hostile, and high-capacity PDW that operates within pistol-format legal definitions. The engineering cost baked into the proprietary operating system and machined billet upper receiver justifies the premium over a $1,200 PSA .300 Blackout AR pistol for users who will exploit its full capabilities. For anyone else, the value proposition diminishes rapidly; if your use case doesn't explicitly demand a folding, sub-10.5-inch barrel .300 BLK platform, a standard AR-15 or a more traditional firearm will provide 90% of the utility for 60% of the cost.