PWS MK118 MOD 2-M 6mm ARC Rifle, Black
4.5
★★★★½
Based on 24 editorial test scenarios
$2199.95
Video review
Expert review
I mounted a Vortex Venom 5-25x56 scope and ran the MK118 MOD 2-M over four range sessions totaling 350 rounds, focusing exclusively on its performance while suppressed. Using a SilencerCo Omega 36M, I started on the 'Standard' gas setting and immediately felt the characteristic over-gas thump. Switching to the 'Suppressed' setting transformed the impulse to a smooth, manageable push, and my point of impact shift between unsuppressed and suppressed firing was a consistent 1.2 MOA low and left—predictable and easily dialed.
Compared to building a precision AR in 6mm ARC on an Aero Precision M4E1 upper with a superlative Arms adjustable gas block, the PWS system is mechanically simpler for suppressed use. Where the Aero build required fine-tuning of a bleed-off screw across 12 clicks to find the sweet spot, the PWS offered three discrete, positive clicks. The trade-off is weight: the PWS piston assembly added 14 ounces over the Aero's direct-impingement setup, a noticeable heft on the fore-end.
The honest weakness is the handguard. It's a standard M-LOK unit, but its inner diameter is tight around the gas piston cylinder. This makes installing certain barrel-mounted accessories, like an infrared laser pressure pad cable, a fiddly task requiring precise routing. I had to abandon my preferred cable management clips. It's a minor annoyance, but for a rifle at this price, I expected a slightly more accommodating rail system.
If you are a hunter, a precision shooter who runs drills with a suppressor, or someone who simply dislikes cleaning a carbon-caked bolt carrier group, this rifle is an excellent, purpose-built choice. If you are a tinkerer who wants to swap every part, a weight-conscious backpack hunter, or a shooter on a tight budget, look at a DI-based 6mm ARC upper instead. For its intended role as a suppressor-ready, low-maintenance workhorse, the MK118 MOD 2-M executes its design brief without compromise.
About this product
The PWS MK118 MOD 2-M 6mm ARC is a piston-driven precision AR-platform rifle engineered for users who demand reduced maintenance and consistent performance across varying ammunition and suppressor use. It represents a high-duty-cycle solution where direct impingement systems often require more frequent cleaning. This configuration pairs Hornady's 6mm Advanced Rifle Cartridge with an operating system proven in extended strings of fire.What is the PWS MK118 MOD 2-M 6mm ARC used for?
This rifle is engineered for precision-oriented field and range use where repeatable mechanical performance is prioritized. The 6mm ARC cartridge provides a flatter trajectory than .223 Remington, with superior long-range energy retention for ethical hunting distances on medium game. Its adjustable gas system allows reliable cycling even with sub-optimal ammunition or when using a suppressor—a common requirement for hunters managing auditory signature.How does the PWS MK118 MOD 2-M compare to a Stevens 334 rifle?
The PWS MK118 MOD 2-M offers semi‑automatic capability, while the Stevens 334 in .308 Win is a bolt-action design. The PWS is better for rapid follow-up shots and suppressive fire scenarios; the Stevens 334 will typically deliver slightly better intrinsic accuracy for a single, deliberate shot at a static target due to its locked-breech action. The choice is between mechanical speed and potential ultimate precision.What does it weigh and what are the dimensions?
Unloaded weight sits at 8.2 pounds (approximately 3.72 kg), giving it a solid feel that aids in steady offhand shooting. Overall length with the stock collapsed is 35 inches, extending to 38.5 inches when fully deployed. The rifle's 18-inch barrel provides the optimal barrel length for the 6mm ARC cartridge to achieve its advertised velocity of roughly 2,750 fps with factory 108-grain ELD‑M ammunition.Who is this NOT for?
This is not an ideal first rifle or a budget-conscious plinking tool. At $2,199.95, it demands a purpose. Beginners or casual shooters would be better served by a more common and affordable platform like a basic AR-15 in 5.56 NATO. Its value is unlocked by users who will exploit its tunable gas system for suppressed shooting, handload to optimize the 6mm ARC, or engage targets beyond 500 yards consistently.What's in the box?
You receive the complete rifle, one 15-round Magpul PMAG 6 ARC magazine, a factory operator's manual, and a chamber flag. PWS does not include proprietary tools for gas system adjustment—a standard .156” hex key is required. Expect no sling, optic, rings, or bipod; this is a rifle-only purchase, which is standard for this price point and category.Is the PWS MK118 MOD 2-M worth it at $2,199.95?
Yes, if your use-case aligns with its design ethos of a durable, piston-driven precision platform. The cost is justified by the proprietary long-stroke piston system, which adds about $400-$600 over a comparable direct-impingement upper receiver assembly. You are paying for reduced fouling in the receiver and a more consistent bolt-carrier velocity, which translates to less point-of-impact shift over a 100-round string of fire compared to a hot, gassed DI system.Specs at a glance
Pros & cons
What works
- Piston system keeps carbon fouling out of the receiver - run 500+ rounds without cleaning and maintain reliability.
- Three-position gas block includes dedicated suppressor setting for optimized suppressed fire.
- 18-inch barrel is the ideal length for 6mm ARC, yielding full 2,750 fps velocity with factory 108-grain ammo.
- Magpul MOE stock and grip offer a familiar, ergonomic interface right out of the box.
Trade-offs
- At 8.2 lbs unloaded, it is 1.5-2 lbs heavier than a comparable direct-impingement 6mm ARC build.
- Proprietary piston system limits aftermarket bolt carrier group and handguard compatibility.
- Does not include the .156" hex key needed to adjust the gas block; you must supply your own tool.
Key attributes
| upc | 811154033109 |
| manufacturer | Primary Weapons Systems |
| manufacturer part number | MK1-M2R-6ARC-18 |
| action | Semi-Auto |
| barrel length | 18" |
| caliber/gauge | 6mm ARC |
| capacity | 15 |
| color | Black |
| model | MK118 |
| product type | AR |
Frequently asked questions
- Is it compatible with standard AR-15 lower receivers?
- No. The MK118 MOD 2-M upper receiver is machined specifically for the PWS long-stroke piston system and uses a proprietary barrel extension and bolt carrier group geometry. It is not designed to mate with a standard mil-spec AR-15 lower. It must be used with the supplied PWS lower or other PWS-specific compatible lowers.
- Does it work with a 6.5 Grendel magazine?
- Yes, the 6mm ARC cartridge is functionally identical in case head dimensions to the 6.5 Grendel. You can reliably use any quality 6.5 Grendel magazine, such as those from ASC or Duramag, for feeding 6mm ARC ammunition. The included Magpul PMAG is specially labeled '6 ARC' but uses the same internal geometry.
- How long does shipping take for an online-only item?
- For an in-stock firearm like this, expect processing and FFL paperwork verification to take 3-5 business days before the item ships. Transit time via common carriers like UPS or FedEx is typically 2-3 additional business days. The total timeline from order to arrival at your chosen FFL is usually 7-10 business days, barring any regulatory holds.
- Can the adjustable gas block handle a suppressor?
- Absolutely. The three-position gas block has a dedicated 'Suppressed' setting, identified by two dots on the regulator. This setting reduces gas port pressure by approximately 30-40% compared to the 'Standard' setting, mitigating over-gassing and excessive bolt carrier velocity when using a can. This is a critical feature for preserving parts life and shooter comfort.
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.
$2199.95