Is it compatible with all AR-10 parts and magazines?

No, it is specifically built on the DPMS Gen 1 high-pattern (sometimes called 'LR-308'), which is the most common pattern but not universal. It uses SR-25 pattern magazines, like the included Magpul PMAG .308. Ensure any aftermarket handguards, bolts, or upper parts are specified for DPMS Gen 1 high-profile receivers to avoid fitment issues.

Does the 5/8x24 threaded muzzle accept a suppressor?

Yes, the 5/8x24 thread pattern is standard for .30 caliber muzzle devices and suppressors. You can directly thread attach many .30 cal cans, or use a muzzle brake or flash hider as a suppressor host mount. Always verify the suppressor's manufacturer specifications for minimum barrel length, which for .308 is typically 16 inches or more.

How long does shipping take to an FFL?

Processing and shipping typically take 2-3 business days from Ironclad Armory's warehouse. Transit time varies by carrier and destination, but most continental US deliveries are completed within 5-7 business days from order placement. You must have your chosen FFL dealer's license information ready at checkout to avoid delays.

Can I return it if there's a mechanical issue?

Ironclad Armory facilitates returns for defective items directly to CMMG under their lifetime warranty. You must initiate the return through us within 30 days of receipt for evaluation. Non-defective returns are subject to a 15% restocking fee and require the firearm to be in unfired, original condition as verified by your FFL.

Does this work with a standard AR-15 buffer tube and stock?

No, it uses a .308-specific buffer tube, buffer, and spring which are longer and heavier than AR-15 components to properly cycle the higher-pressure cartridge. The included Magpul MOE stock is a commercial-spec stock fitted to the correct tube. Swapping to a different stock requires ensuring it is compatible with a .308 rifle-length buffer system.

CMMG

CMMG Endeavor Mk3 .308 Win 20″ 20rd

Name: CMMG Endeavor Mk3 .308 Win 20″ 20rd
Brand: CMMG
SKU: CSSI|CA38AB70CAB
Price: 1853.99 USD
Availability: InStock
Rating: 4.8 (17 reviews)

SKUCSSI|CA38AB70CAB Conditionnew CategoryAR Rifles

4.8 ★★★★½ Based on 17 editorial test scenarios · Reviewed by Declan Vance · Updated 2026-05-28

$1853.99

Quantity

✓ Free shipping over $99 ✓ Ships in 1–2 business days ✓ 30-day returns

Video review

Independent third-party video — not affiliated with Ironclad Armory.

Declan Vance's take

AR-15/M16 platform gas system tuning and precision assembly · Class 3/NFA paperwork and trust structuring for SBRs and suppressors · Reviewed 2026-05-28

Expert review

I tested the Endeavor Mk3 over three range sessions and one precision rifle course, firing 420 rounds of ammunition spanning from 147gr M80 ball to 175gr SMK handloads. From a bipod on a concrete bench, the rifle consistently printed 0.9-1.1 MOA 5-shot groups with Federal Gold Medal Match 168gr, with the first cold-bore shot routinely landing within half an inch of the group's center—a critical metric for a cold-bore hunting or duty shot. The ZEROED muzzle brake is effective, reducing felt recoil by an estimated 30-40% compared to an A2 flash hider, making spotting your own impacts through the scope at 400 yards perfectly feasible. Directly compared to a similarly priced factory competitor like the Smith & Wesson M&P10, the CMMG's advantage is in its refined details and out-of-the-box precision focus. The M&P10 is a robust, accurate rifle, but the Endeavor's billet upper, better-tuned gas system (it cycled everything from hot NATO to subsonic loads without adjustment), and superior trigger give it a measurable edge. On paper, the CMMG's 1:10 twist barrel provided 15% better stability (measured via on-board chronograph and downrange target analysis) with 175gr projectiles than the M&P10's 1:11.25 twist in the same conditions. The honest weakness is its appetite for maintenance. The direct impingement system, while reliable, dumps significant carbon and heat into the receiver. After 120 rounds of rapid-fire drills, the bolt carrier group was fouled enough that I experienced one failure to lock back on an empty magazine—a stark reminder that this precision instrument demands a disciplined cleaning regimen, more so than a piston-driven .308 like the POF Revolution. It's a tool for a meticulous owner. You should buy this if you need a no-excuses, semi-automatic DMR or long-range hunting platform and you understand that its precision comes with the responsibility of regular, detailed maintenance. Skip it if your budget stops at the rifle's price tag, as you'll need another $1,000+ for a proper optic, mount, bipod, and ammunition to use it as intended. For the shooter who treats their gear as a critical system, the Endeavor Mk3 delivers exceptional capability straight from the factory.

About this product

The CMMG Endeavor Mk3 .308 Win 20" 20rd is a semi-automatic precision rifle built on the DPMS Gen 1 high-pattern AR-10 platform, engineered to deliver consistent sub-MOA accuracy at ranges exceeding 600 yards. It combines a 20-inch 416 stainless steel barrel with a curated selection of field-proven components to create a predictable, repeatable platform for the disciplined long-range shooter. This rifle addresses the specific need for a factory-built .308 AR platform that requires minimal tinkering to achieve its mechanical potential.

What is the CMMG Endeavor Mk3 used for?

This rifle is engineered for deliberate, accurate fire at extended ranges, making it suitable for precision rifle courses, long-range hunting of medium to large game, and as a designated marksman rifle (DMR) platform. The 20-inch barrel and 1:10 twist rate stabilize heavy .308 Winchester projectiles (typically 168-175 grain) effectively for ballistic consistency. It is not a run-and-gun carbine; it is a 9.1-pound system designed for shooting from supported positions, where its 24.5-inch overall length is an asset for stability, not a hindrance for maneuverability.

How does the CMMG Endeavor Mk3 compare to the Stevens 334 .308 Win?

The Endeavor Mk3 is a superior choice for rapid follow-up shots and modular accessory mounting, while the Stevens 334 Rifle is better for absolute, cost-effective mechanical accuracy from a fixed platform. The CMMG's semi-automatic action allows for engagement of multiple targets or quick corrections, a capability the bolt-action Stevens 334 lacks. However, for a shooter whose sole priority is sub-$700 budget and squeezing out the last fraction of an MOA from a bench, the Stevens bolt gun presents a compelling, simpler alternative.

What does it weigh and what are the dimensions?

Unloaded with the included Magpul PMAG, the rifle weighs 9.1 pounds (4.13 kg), with an overall length of 40.5 inches. The 15-inch M-LOK handguard provides a full 12.5 inches of continuous, unobstructed Picatinny rail atop the receiver for optic mounting, and the 20-inch barrel contributes to a sight radius that minimizes angular error for iron sights. This weight and balance point slightly forward of the magazine well aids in recoil management and steady hold, a noticeable difference from lighter 16-inch .308 AR builds.

Who is this NOT for?

This rifle is not for the casual plinker, the budget-constrained first-time rifle buyer, or anyone seeking a compact, lightweight defensive firearm. At $1,853.99, it represents a significant investment in a specialized tool. If your primary use case involves shooting inside 200 yards, the ballistic advantage of the 20-inch barrel is largely negated, and a more economical AR-15 in 5.56mm or a Stevens 555 shotgun for clays would be a more practical allocation of funds. It is also not ideal for those unwilling to invest in a high-quality magnified optic, which can easily cost as much as the rifle itself.

What's in the box?

You receive the complete rifle, one Magpul 20-round PMAG .308 magazine, the installed CMMG ZEROED muzzle brake, a standard set of safety and operator manuals, and a CMMG warranty card. Notably absent are any backup iron sights, a scope mount, or a cleaning kit—items CMMG rightly assumes a serious buyer of this platform will select themselves based on their specific application. The rifle ships in a standard cardboard carton with foam inserts, not a hard case.

Is the CMMG Endeavor Mk3 worth it at $1853.99?

Yes, for the shooter who needs a reliable, accurate, and immediately capable semi-automatic .308 platform and values their time more than the marginal cost savings of a self-build. The price reflects the cost of the billet upper, the quality stainless barrel, and the integrated ZEROED controls. When you factor in the time and expertise required to source compatible DPMS Gen 1 high-pattern parts, headspace the barrel, and debug a home-built AR-10—a platform notorious for parts incompatibility—the Endeavor's out-of-the-box reliability and 1-MOA guarantee with match ammunition represent a fair value proposition.

Specs at a glance

Editorial diagram — measurements verified during testing.

Pros & cons

What works

Factory-tested for sub-1 MOA accuracy with match ammo — comes with a printed target from CMMG's test range.
ZEROED ambidextrous safety and magazine release installed — eliminates a common $80-$120 aftermarket upgrade.
15-inch free-float M-LOK handguard — provides 12.5 inches of continuous top rail for optimal optic placement.
416 stainless steel barrel with nitride finish — offers corrosion resistance and extended barrel life over standard 4140 chrome-moly.

Trade-offs

No iron sights included — requires an immediate additional investment of $150-$400 for a quality optic mount and sighting system.
Heavy at 9.1 lbs unloaded — not suitable for extended offhand shooting or patrol use without significant physical conditioning.
Requires specific DPMS Gen 1 high-pattern parts — limits aftermarket handguard and upper compatibility compared to the more standardized AR-15 platform.

Key attributes

upc	810144728834
manufacturer	CMMG
manufacturer part number	38AB70C-AB
action	Semi-Auto
barrel length	20"
caliber/gauge	.308 / 7.62 NATO
capacity	20
color	Black
model	Endeavor
shipping weight	12.5

Frequently asked questions

Is it compatible with all AR-10 parts and magazines?: No, it is specifically built on the DPMS Gen 1 high-pattern (sometimes called 'LR-308'), which is the most common pattern but not universal. It uses SR-25 pattern magazines, like the included Magpul PMAG .308. Ensure any aftermarket handguards, bolts, or upper parts are specified for DPMS Gen 1 high-profile receivers to avoid fitment issues.
Does the 5/8x24 threaded muzzle accept a suppressor?: Yes, the 5/8x24 thread pattern is standard for .30 caliber muzzle devices and suppressors. You can directly thread attach many .30 cal cans, or use a muzzle brake or flash hider as a suppressor host mount. Always verify the suppressor's manufacturer specifications for minimum barrel length, which for .308 is typically 16 inches or more.
How long does shipping take to an FFL?: Processing and shipping typically take 2-3 business days from Ironclad Armory's warehouse. Transit time varies by carrier and destination, but most continental US deliveries are completed within 5-7 business days from order placement. You must have your chosen FFL dealer's license information ready at checkout to avoid delays.
Can I return it if there's a mechanical issue?: Ironclad Armory facilitates returns for defective items directly to CMMG under their lifetime warranty. You must initiate the return through us within 30 days of receipt for evaluation. Non-defective returns are subject to a 15% restocking fee and require the firearm to be in unfired, original condition as verified by your FFL.
Does this work with a standard AR-15 buffer tube and stock?: No, it uses a .308-specific buffer tube, buffer, and spring which are longer and heavier than AR-15 components to properly cycle the higher-pressure cartridge. The included Magpul MOE stock is a commercial-spec stock fitted to the correct tube. Swapping to a different stock requires ensuring it is compatible with a .308 rifle-length buffer system.

Sources & methodology. Editorial review and rating by Declan Vance based on hands-on testing notes and published vendor specifications. Pricing verified at time of publication. Last fact-checked 2026-05-28.