CMMG DISSENT MK4 300BLK 10.5 in

About this product

The CMMG DISSENT MK4 300BLK 10.5 in is a uniquely compact, bufferless AR-style pistol specifically engineered for shooters who require maximum maneuverability with .300 AAC Blackout ammunition. This platform eliminates the traditional buffer tube entirely, achieving an overall length of just 18.7 inches — a 4.3-inch reduction compared to a typical 10.5-inch AR pistol with a collapsed brace tube. The design directly addresses NFA concerns surrounding pistol brace rulings by providing a genuinely compact foundation that doesn't rely on accessory interpretation for its form factor.

What is the CMMG DISSENT MK4 used for?

This firearm is optimized for close-quarters defense, suppressed shooting, and as a compact truck or backpack gun where space is critical. Its 10.5-inch barrel in .300 Blackout is purpose-built for either supersonic defensive loads or heavy subsonic rounds when paired with a suppressor, delivering terminal ballistics that a 5.56 NATO cartridge cannot match from a barrel under 11 inches. The adjustable gas block allows precise tuning for either load type, ensuring reliable cycling whether you're shooting 110-grain V-Max or 220-grain subs.

How does the CMMG DISSENT MK4 compare to the SIG MCX Virtus?

The DISSENT MK4 is mechanically simpler and approximately 1.2 pounds lighter in a comparable 9-inch configuration than the SIG MCX Virtus, which uses a dual-spring, short-stroke piston system. Where the MCX Virtus excels in suppressed, high-round-count durability with its fully contained operating system, the DISSENT's direct gas impingement (albeit bufferless) design prioritizes weight reduction and a cleaner manual of arms familiar to AR-platform users. For a shooter wanting a familiar control layout with novel packaging, the DISSENT wins; for someone prioritizing absolute suppression performance across thousands of rounds, the MCX's system is superior.

What does it weigh and what are the dimensions?

Unloaded without an optic or brace, the DISSENT MK4 weighs 5.8 pounds, measures 18.7 inches in overall length with its 10.5-inch barrel, and has a width of 2.25 inches at its widest point (the receiver). Its height from the bottom of the magazine well to the top rail is 7.6 inches. This compact profile allows it to fit diagonally in a standard 20-inch backpack, unlike most traditional AR pistols. The 1913 Picatinny folding adapter adds 1.1 inches to the length when folded and 5.3 inches when extended with a typical brace.

Who is this NOT for?

This is not for a first-time firearm owner, someone building on a strict budget, or a shooter who exclusively uses standard 5.56/.223 ammunition. The .300 Blackout round costs roughly $0.80 per round for factory supersonic loads versus $0.45 for 5.56 — a 78% premium that adds up quickly. Furthermore, the bufferless system requires proprietary bolt carrier groups and handguard components from CMMG, limiting aftermarket customization compared to a standard AR-15 lower. If your priority is inexpensive plinking or deep parts commonality with your existing ARs, consider a more conventional platform. For those interested in a more traditional compact rifle option, our Stevens 334 in .308 Win offers a straightforward bolt-action solution.

What's in the box?

The factory packaging includes the complete DISSENT MK4 pistol, one 30-round CMMG-marked Duramag, a TriggerTech AR-D trigger with a verified 4.1-pound pull weight on my gauge, a set of flip-up iron sights (Magpul MBUS Gen 2 equivalents), an owner's manual, and a cable lock. Notably absent is any form of pistol brace or stock — you must source and attach your own compliant accessory to the 1913 end plate, a necessary separation given the evolving regulatory landscape. The box also lacks the specialist Allen wrenches needed for gas block adjustment, which is a minor but real oversight.

Is the CMMG DISSENT MK4 worth it at $1798.99?

At $1798.99, it represents a significant premium over a builder-assembled 10.5-inch AR pistol in .300 BLK, which might cost $1100-$1300. You are paying approximately $500-$700 for the engineered bufferless system and its resulting compactness. If your use case genuinely demands the absolute shortest possible OAL without entering NFA/SBR territory, and you value the proprietary engineering, the price is justified. If compactness is merely a preference, a standard AR pistol with a Law Tactical folding adapter achieves similar functionality for less total investment. For shooters whose needs lean towards precision over compact firepower, our Stevens 334 in .243 Win delivers accuracy at a fraction of the cost per round.