There comes a point when you want an AR-format platform that breaks the mold: a rifle that keeps the familiar ergonomics and modularity of the AR-15 family while delivering increased terminal performance and suppression-friendly behavior. For shooters who value a battle-tested platform tuned for heavier bullets, the CMMG RESOLUTE MK4 [AB] stakes a strong claim in that niche.
CMMG RESOLUTE MK4 [AB] arrives as a purpose-built hybrid: mil-spec receiver set engineered to chamber intermediate cartridges such as 5.56x45mm NATO in a traditional rifle layout, now adapted to Hornady’s .338 ARC for 2025. The Banshee-derived Mk4 retains a traditional buffer tube operation for broad stock compatibility and comes equipped with a Z-series muzzle brake and CMMG’s EML15-series M-LOK handguard. Shop this product
Design and Build: Familiar AR ergonomics with large-bore intent
The RESOLUTE MK4 [AB] keeps the skeleton that makes the AR-15 family so adaptable: a mil-spec receiver set and traditional buffer tube operation that embraces a wide range of stock options. The 16.1-inch barrel length hits a practical sweet spot — long enough to exploit the .338 ARC’s ballistics while remaining maneuverable for field and defensive use. Finished in Armor Black Cerakote, the rifle resists wear and looks the part on any range or duty belt.
EML15-series M-LOK Handguard
CMMG’s EML15 handguard brings a slim, modular mounting surface in M-LOK format. It balances accessory mounting options, weight savings, and positive handling — ideal when you mount optics, lights, or a vertical grip. The Z-series muzzle brake paired with the EML15 setup helps manage recoil impulse of the .338 ARC without dramatically increasing blast into the shooter’s face when un-suppressed.
Caliber Focus: .338 ARC — why it matters
.338 ARC is the centerpiece of this build. Designed to give AR-platform users the ability to push heavy-for-size projectiles with consistent energy, the cartridge bridges roles between heavy subsonic/supersonic utility and short-action long-range capability. Compared to platforms like .300 BLK, .338 ARC delivers increased on-target energy and is less sensitive to gas system tuning when transitioning between suppressed and unsuppressed configurations — an important factor for operators and hunters who value consistency.
Applications and performance envelope
Use cases for the RESOLUTE MK4 [AB] in .338 ARC include medium game hunting, long-range precision in a carbine-sized package, and robust defensive performance where extra terminal energy is desired. The cartridge’s heavier bullets give better retained energy past barrier materials and downrange, while the 16.1-inch barrel allows reasonable velocity without forcing an unwieldy-length rifle.
Controls, Stocks, and Included Accessories
The traditional buffer tube action means the rifle is compatible with a wide selection of buttstocks. The included Ripstock buttstock offers a durable, adjustable interface, and the overall setup remains familiar to anyone trained on AR controls. CMMG ships one 10-round magazine with the rifle, compliant with many jurisdictions while allowing immediate function testing on the range. At a listed price of $1507.99, the RESOLUTE MK4 [AB] presents a compelling value for a factory-built AR-style carbine optimized for .338 ARC.
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Ergonomics and Range Handling
Expect familiar AR ergonomics with a slightly different recoil character due to the .338 ARC’s larger projectile. The Z-series muzzle brake tames muzzle rise and helps the shooter maintain follow-up shot speed. The EML15 handguard keeps the rifle balanced and provides rock-solid mounting points for optics and support accessories. For training and practice, plan on ammunition costs higher than 5.56; the cartridge rewards careful shot placement and ammunition selection.
Maintenance and modularity
Maintenance follows standard AR patterns: field-strip, clean the gas system as required, and maintain the barrel and brake. The mil-spec receiver set and buffer tube mean you can swap stocks and many aftermarket components without permanent modification, keeping modularity high for mission-specific setups.
Who should consider the RESOLUTE MK4 [AB]?
If you want the ergonomics, controls, and accessory ecosystem of an AR-platform rifle but need greater terminal performance than 5.56 can offer, the RESOLUTE MK4 [AB] is worth evaluating. Hunters moving to a short-action, high-energy cartridge, shooters who want heavier supersonic or subsonic capabilities with less gas tuning headaches, and operators seeking a compact hard-hitting carbine will find this package attractive. The combination of the 16.1-inch barrel, EML15 handguard, Ripstock, Z-series brake, and Armor Black Cerakote creates a balanced, rugged tool out of the box.
Technical features and careful component selection make this a standout option for those who want large-bore performance in a familiar platform. For more details and to purchase from the retailer, Shop this product here.
People Also Ask
What makes this product stand out from competitors?
This product offers superior quality and innovative features that set it apart in the market. Its design focuses on both performance and reliability, making it a top choice for professionals and enthusiasts alike.
Is this product suitable for beginners?
Yes, this product is designed with user-friendly features that make it accessible to beginners while still offering advanced capabilities for experienced users.
What warranty or support is available?
The product comes with comprehensive warranty coverage and excellent customer support to ensure your satisfaction and peace of mind.
How does this compare to similar products in its price range?
This product offers exceptional value for its price point, providing features and quality that typically cost significantly more in comparable alternatives.
What maintenance is required?
Minimal maintenance is required thanks to the product’s durable construction and quality materials. Regular cleaning and occasional inspections will keep it performing optimally.
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