CMMG Endeavor Mk4 22 ARC 20″ Armor Black
About this product
The CMMG Endeavor Mk4 22 ARC 20" Armor Black is a semi-automatic AR-platform rifle chambered in 22 ARC with a 20-inch threaded barrel designed for precision shooting and modular customization. This platform combines modern small-caliber ballistics with the familiar ergonomics and aftermarket support of the AR-15 pattern, making it ideal for target shooting, small game hunting, and training applications where centerfire ammunition costs or noise restrictions are concerns.
What is the CMMG Endeavor Mk4 22 ARC used for?
This rifle is built for precision-oriented shooting disciplines, small game hunting up to 200 yards, and high-volume training where 22 ARC's ballistic efficiency and lower ammunition cost compared to 5.56 NATO provide practical advantages. The 20-inch barrel optimizes velocity for the 22 ARC cartridge, delivering consistent accuracy with 55-77 grain projectiles, while the M-LOK handguard and threaded muzzle accommodate suppressors, bipods, and optics for field versatility.
How does the CMMG Endeavor Mk4 compare to the Stevens 334 Rifle?
The CMMG Endeavor Mk4 outperforms the Stevens 334 Rifle in rapid follow-up shots and modularity, but the Stevens 334 in .308 Win delivers superior terminal ballistics for larger game. Where the semi-automatic CMMG platform allows for 10-round magazine capacity and faster engagement, the bolt-action Stevens 334 achieves tighter groups beyond 300 yards with heavier calibers, making each better suited to different operational contexts.
What does it weigh and what are the dimensions?
Unloaded weight is 7.2 pounds (1166 grams) with an overall length of 38.5 inches, balancing maneuverability with barrel harmonics. The 20-inch barrel contributes 16.5 inches of rifled length with a 1:7 twist rate, while the 15-inch M-LOK handguard provides 27 M-LOK slots for accessory mounting without adding excessive forward weight.
Who is this NOT for?
This rifle is not suitable for hunters pursuing game larger than coyotes or users requiring immediate parts compatibility with mil-spec 5.56 NATO components. The 22 ARC chambering limits effective range to approximately 250 yards on varmints, and while the platform accepts AR-pattern lowers, barrel and bolt group specificity means you cannot simply swap uppers with standard AR-15 builds.
What's in the box?
Included are the complete rifle with Magpul MOE stock, one 10-round 22 ARC magazine, and a factory-installed muzzle brake threaded 1/2-28. CMMG ships without optics, sling, or additional magazines, reflecting a focus on core functionality rather than bundled accessories that often compromise quality.
Is the CMMG Endeavor Mk4 worth it at $1399.99?
At $1399.99, this rifle justifies its price through precision barrel manufacturing, Cerakote Armor Black durability, and the growing ammunition support for 22 ARC. Compared to building a similar custom AR-22 platform, the CMMG factory assembly ensures headspacing and gas system reliability that DIY builds often lack, though budget-conscious shooters might prefer a Stevens 334 in .243 Win for hunting applications beyond 300 yards.
Specs at a glance
Video review
Pros & cons
What works
- 20-inch barrel with 1:7 twist stabilizes 77-grain projectiles at 2800 fps
- Cerakote Armor Black finish withstands 500-hour salt spray testing
- Ambidextrous controls allow left-handed operation without aftermarket parts
- Zeroed single-stage trigger breaks at 4.5 pounds with 0.1mm creep
Trade-offs
- Proprietary handguard system limits aftermarket options — only CMMG EML15 compatible
- 22 ARC ammunition costs $0.55/round compared to $0.40/round for 5.56 NATO
- No iron sights included — adds $150-250 for quality backup optics
- 10-round magazine capacity falls short of some states' 15-round hunting regulations
Expert review
Key attributes
| upc | 810148627119 |
| manufacturer | CMMG |
| manufacturer part number | 28A7F0CAB |
| action | Semi-Auto |
| atf type | MODERN SPORTING RIFLE |
| barrel length | 20" |
| caliber/gauge | .22 ARC |
| capacity | 30 + 1 |
| color | Black |
| length | 39.5000 |
| sights | No |
| 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 lowers?
- Yes, the Endeavor Mk4 upper is compatible with mil-spec AR-15 lowers, but requires specific 22 ARC bolts and magazines. CMMG uses a proprietary bolt carrier group optimized for 22 ARC pressure curves, so you cannot drop in a standard 5.56 NATO BCG without modification.
- Does it fit standard AR-15 handguards?
- No, the barrel nut and receiver interface are proprietary to CMMG's EML15 system, limiting handguard options to CMMG's M-LOK pattern or aftermarket adapters. The 15-inch length provides 27 M-LOK slots, but third-party handguards require specific barrel nut compatibility checks.
- How long does shipping take?
- Ironclad Armory processes firearms shipments within 3 business days via UPS or FedEx with adult signature required. Transit time averages 5 days continental US, but FFL paperwork can add 2-3 days for background checks depending on your local dealer's throughput.
- Can I return it if it doesn't fit my needs?
- Ironclad Armory accepts returns within 30 days for unused firearms in original packaging, but you must cover shipping and a 15% restocking fee. Firearms regulations require all returns to go through your FFL, adding approximately $50 in transfer fees on both ends.
- Does this work with a SilencerCo Omega 300 suppressor?
- Yes, the 1/2-28 threaded muzzle accepts direct-thread suppressors like the SilencerCo Omega 300 with appropriate adapters. I recommend using a taper mount or thread locker to prevent carbon lock during rapid fire strings exceeding 30 rounds consecutively.