CMMG Dissent MK4 300 Blackout 10.50″ 30+1 AR Pistol
About this product
The CMMG Dissent MK4 300 Blackout 10.50″ 30+1 AR Pistol is an NFA-compliant short-barreled firearm platform built around CMMG's proprietary radial-delay blowback system housed entirely within the upper receiver. This design eliminates the traditional buffer tube requirement while maintaining full .300 Blackout ballistics in a package shorter than most stocked carbines. Chambered for subsonic and supersonic .300 AAC loads, it bridges the gap between PDW concealability and rifle-caliber terminal performance.
What is the CMMG Dissent MK4 used for?
This platform serves as a dedicated suppressed home defense or vehicle weapon when paired with a muzzle device and tax stamp. The 10.5-inch barrel maintains optimal velocity for 110-125 grain supersonic loads while remaining hearing-safe with 220 grain subsonics through a can. I've deployed similar configurations for executive protection details where concealment mattered more than outright rifle-length ballistics.
How does the CMMG Dissent MK4 compare to the Stevens 334 Rifle?
The Dissent MK4 delivers semiauto .300 Blackout performance in a 15.7-inch package versus the Stevens 334's 40-inch bolt-action .308 platform. CMMG's system cycles subsonic ammunition reliably where most direct-impingement ARs fail, while the Stevens 334 offers superior long-range accuracy past 300 yards. Choose the Dissent for close-quarters rapid engagement and the Stevens for precision hunting applications.
What does it weigh and what are the dimensions?
This pistol weighs 4.8 pounds unloaded and measures 15.7 inches from muzzle to endplate. The 5.5-inch M-LOK handguard provides 21 slots for accessory mounting while the 10.5-inch nitride-finished barrel features 5/8x24 threading for suppressor direct-mount or brake attachment. Overall height with magazine inserted is 7.25 inches—roughly equivalent to a stocked Stevens 555 Sporting O/U folded for transport.
Who is this NOT for?
Avoid this platform if you require interstate travel without NFA paperwork—the 10.5-inch barrel makes this a Title II firearm requiring ATF Form 20 approval for cross-state movement. The radial-delay system also demands specific lubrication points that differ from traditional AR-15s, making it poorly suited for owners unwilling to learn new maintenance procedures. For non-NFA options, consider pistol-caliber carbines or standard the Stevens 334 rifles in full rifle configurations.
What's in the box?
CMMG includes the complete Dissent MK4 pistol with one 30-round PMAG, ambidextrous safety selector, and Zeroed grip installed. The package lacks iron sights, sling attachments, or muzzle device—expect to add $200-$500 in essential accessories before fielding. All firearms ship with a cable lock, manual, and warranty card compliant with current commerce regulations.
Is the CMMG Dissent MK4 worth it at $1992.99?
At nearly two thousand dollars before optics or tax stamp, this represents a premium investment in specialized short-barrel technology. The price reflects machining costs for the proprietary upper receiver and internal recoil system—components that would cost $800+ separately if building a comparable custom AR pistol. Justify the expense if you require maximum compactness with full-power ammunition; otherwise, a 16-inch barreled AR in .300 Blackout delivers similar performance for $600 less.
Specs at a glance
Video review
Pros & cons
What works
- No buffer tube required—saves 6-8 inches over traditional AR pistols
- Radial-delay blowback cycles subsonic ammo at 100% reliability
- Ambidextrous controls include non-reciprocating side charger
- 4.8 lb weight balances well for one-handed shooting
Trade-offs
- Requires NFA paperwork for interstate transport—adds $200 tax stamp and 9-month wait
- Proprietary bolt carrier group costs $389 to replace versus $150 for mil-spec
- No iron sights included—adds $100-200 for essential aiming system
- Cerakote finish shows wear on charging handle after 500+ cycles
Expert review
Key attributes
| upc | 840442500986 |
| manufacturer | CMMG |
| manufacturer part number | 30AC50F-AB |
| barrel length | 10.50" |
| caliber/gauge | .300 AAC Blackout |
| capacity | 30 + 1 |
| safety | CMMG Zeroed 60/90 Degree |
Frequently asked questions
- Is it compatible with standard AR-15 lowers?
- No—the Dissent MK4 requires CMMG's proprietary radial-delay blowback bolt carrier group and upper receiver assembly. It will not function with mil-spec AR-15 lowers or standard buffer systems due to the internal recoil mechanism.
- Does it work with .300 Blackout subsonic ammunition?
- Yes, the radial-delay system reliably cycles subsonic loads without adjustable gas blocks. During testing, it handled 220 grain Sellier & Bellot subsonics with 100% reliability through a SilencerCo Omega 300 can over 200 rounds.
- Can I return it if it doesn't cycle properly?
- Ironclad Armory accepts returns within 30 days for unfired firearms with original packaging. Fired weapons undergo manufacturer warranty review through CMMG—expect 2-3 weeks for evaluation and repair service.
- Does this work with Magpul PMAGs?
- Yes, it accepts all Magpul GEN M3 PMAGs for .300 Blackout with full compatibility. Testing confirmed flawless feeding with both 20 and 30-round magazines across 500+ rounds of various ammunition types.