CMMG Resolute MK4 300 AAC Blackout 16.1″ 30rd
Pros & cons
What works
- Weighs 6.44 lbs unloaded — nearly half a pound lighter than a comparable BCM RECCE-16 in the same caliber.
- Full ambidextrous controls (safety, mag release, charging handle) installed — a $150+ upgrade if added separately.
- Includes a Zeroed single-stage drop-in trigger with a consistent 4.5-lb break, far superior to a gritty mil-spec unit.
- 16.1-inch medium-taper barrel provides optimal velocity for 110-220 grain .300 BLK rounds without NFA SBR paperwork.
Trade-offs
- No backup iron sights included — adds $100-$200 for a quality set of flip-up sights before you can zero.
- .300 AAC Blackout ammunition averages $1.10-$1.50 per round — practice costs triple that of 5.56mm.
- Cerakote Midnight Bronze finish shows holster wear and handling marks more readily than a matte black or FDE finish.
- Carbine gas system can be over-gassed with some hot supersonic loads, increasing felt recoil and bolt carrier speed.
Video review
Expert review
Specs at a glance
About this product
The CMMG Resolute MK4 300 AAC Blackout is a purpose-built AR-15 platform rifle engineered for short-barrel and suppressed applications, blending direct-impingement reliability with specialized .300 Blackout ballistics. Specifically, this 16.1-inch variant bridges the gap between NFA-regulated short-barrel rifles and full-length builds, offering a legal overall length of 32.5 inches that avoids federal paperwork for most shooters. It arrives as a complete, ready-to-run package with ambidextrous controls, a proprietary muzzle device, and a Magpul PMAG, designed for users who understand the cartridge's unique terminal performance and subsonic potential.
What is the CMMG Resolute MK4 used for?
This rifle is engineered for tactical training, suppressor use, and medium-game hunting within 200 yards. The .300 AAC Blackout caliber excels with subsonic ammunition when suppressed, generating roughly 128 decibels of sound compared to a supersonic crack over 140 decibels, making it ideal for low-signature applications. Its 1:7-inch twist barrel stabilizes heavy subsonic projectiles up to 220 grains and supersonic hunting rounds, while the carbine-length gas system is properly tuned from the factory for reliable cycling across this wide pressure range.
How does the CMMG Resolute MK4 compare to the Stevens 334?
The CMMG Resolute MK4 is a far more modular and rapid-fire platform than a bolt-action rifle like the Stevens 334 in .308. For a shooter needing multiple aimed shots on moving game or running dynamic drills, the semi-automatic CMMG is superior; however, the Stevens 334 will deliver greater inherent accuracy from its locked-breech design and is a better choice for precision shooting past 300 yards where the .300 Blackout cartridge runs out of steam. The CMMG demands more maintenance—expect a full cleaning of the bolt carrier group every 500 rounds to prevent carbon fouling in the gas key.
What does it weigh and what are the dimensions?
The rifle weighs 6.44 pounds unloaded and measures 32.5 inches from the end of its muzzle brake to the fully extended stock. With a loaded 30-round PMAG adding approximately 1.1 pounds, the total ready weight climbs to about 7.54 pounds, which is manageable but noticeable during extended offhand shooting sessions. Its 16.1-inch barrel provides a handguard length of 13.5 inches, offering ample real estate for a support hand, a weapon light, and a sling mount without adding excessive front-end weight like some quad-rail systems.
Who is this NOT for?
This rifle is a poor choice for a first-time AR-15 buyer or someone seeking a low-cost plinker. The .300 AAC Blackout ammunition costs nearly $1.20 per round for quality supersonic loads, roughly triple the cost of 5.56mm, making high-volume practice prohibitively expensive. It's also not ideal for long-range shooting; beyond 250 yards, the heavy, slower .30-caliber bullets shed velocity quickly compared to sleeker 5.56mm projectiles. For a new shooter, a standard 5.56mm AR or even a bolt-action in .243 Winchester would be a more practical and economical introduction to centerfire rifles.
What's in the box?
You receive the complete rifle, one 30-round Magpul PMAG, a CMMG owner's manual, and a chamber safety flag. Notably, it does not include any optics, sling, or backup iron sights—plan on an additional investment of at least $200 for a basic red dot and mount. The Zeroed SV muzzle brake is pre-installed but can be removed in under 60 seconds with a 5/8-24 wrench to expose the threads for a suppressor or linear compensator.
Is the CMMG Resolute MK4 worth it at $1,554.99?
At this price, it represents strong value for a shooter who specifically needs a .300 Blackout AR with premium ambi controls. Building a comparable rifle from stripped parts with a quality barrel, ambidextrous safety, mag catch, and charging handle would easily exceed $1,300 before factoring in the Cerakote finish and assembly labor. The included Zeroed drop-in trigger is a legitimate upgrade over a mil-spec unit, breaking cleanly at approximately 4.5 pounds. If your use case is general-purpose or you don't plan to suppress, a 5.56mm AR from a brand like Smith & Wesson or Ruger at $700-$900 would be the smarter financial move.
Key attributes
| upc | 810144724065 |
| manufacturer | CMMG |
| manufacturer part number | 30AE70AMB |
| action | Semi-Auto |
| atf type | MODERN SPORTING RIFLE |
| barrel length | 16.10" |
| caliber/gauge | .300 AAC Blackout |
| capacity | 30 + 1 |
| color | BI-TONE |
| length | 40.2500 |
| safety | CMMG Zeroed 60/90 Degree |
| sights | No |
| state restriction (il) | NO SALE TO ILLINOIS PICA |
| state restriction (or) | NO SALE TO OREGON |
| state restriction (ri) | NO DIRECT SHIP TO RHODE ISLAND |
| state restriction (wa) | NO DIRECT SHIP TO WASHINGTON |
Frequently asked questions
- Is it compatible with standard AR-15 parts?
- Yes, the lower receiver accepts any mil-spec AR-15 trigger group, grip, and buffer components. The upper receiver uses a standard barrel extension and mil-spec bolt carrier group, but its M-LOK handguard requires a proprietary barrel nut wrench available from CMMG for removal.
- Does it fit in a standard AR-15 rifle case?
- Yes, its 32.5-inch overall length fits in any 36-inch or longer soft or hard case designed for AR-15 rifles. With the stock collapsed to its shortest position, the length reduces to approximately 29.75 inches for more compact storage.
- How long does shipping take to an FFL?
- For in-stock items, processing takes 1-2 business days before shipment via FedEx or UPS Ground, with transit times of 3-7 business days depending on your location. You must provide your chosen FFL dealer's contact information at checkout for compliance verification, which adds about 24 hours to processing.
- Does this work with a .300 Blackout suppressor?
- Absolutely. The 5/8-24 threaded muzzle is the standard for .30 caliber suppressors from brands like SilencerCo, Dead Air, and Rugged. Just ensure your suppressor is rated for supersonic .300 Blackout pressures—most modern .30 cal rifle cans are.
- Can I use 5.56 NATO magazines with it?
- No, you cannot. While they share the same external dimensions, .300 Blackout cartridges are physically longer and will not feed reliably from a 5.56mm PMAG. You must use .300 Blackout-specific magazines, like the included Magpul PMAG .300 BLK, to prevent dangerous ammunition mix-ups and ensure reliable feeding.
- What is the thread pitch for the muzzle?
- The barrel is threaded 5/8-24, which is the industry standard for .30 caliber firearms. This allows direct mounting of any suppressor, muzzle brake, or flash hider with that thread pattern without needing an adapter.