A few weeks ago Jeremy S handed me a Primary Weapon Systems MK116 Mod 2 rifle. As I’ve been busy shooting various piston driven AR15s, I was curious to see if a high end version is worth an extra grand or two.
PWS ships the MK116 Mod 2 rifle equipped with a BCM stock, grip and charging handle to match. The rifle’s buffer tube holds the stock using PWS’ proprietary ratchet lock system, eliminating the need for pinning. You can easily remove and replace the buffer tube with a tunable buffer system like CapArms Quiet Shuttle Tunable Buffer System.
The grip compartment contains an Allen key and a rifle servicing tool for adjusting the piston and removing the rail. The BCM stock and the lower receiver end plate sport quick detach sockets, a feature offered by any modern rifle worth its salt.
PWS went full ambi on the MK116: magazine release, bolt catch and safety selector. One thing to note: this is the only AR I’ve ever encountered that doesn’t contain a forward assist. Not a big issue; the bolt contains a spring at the end which helps it stay in battery.
PWS shipped the MK116 to TTAG with a BCM trigger. As they sell the gun with a ZEV Tech SSR trigger, we installed one. With its bronze color it stood out like Beelzebub at an All Saints Day mass. The ZEV trigger breaks crisply at 5.5 lbs. with a light reset. Too light by my tastes; it made it hard for me to fire consistent rapid strings.
The barrel is a full length 16.1 inch in .223 Wylde with a 1:8 twist. It’s wrapped in PWS’s proprietary PicMod rail, which comes standard with RailScales and a BCM KMSM QD sling mount.
A three position gas piston selector — normal, low and extra low — sits at the far end of the barrel. PWS includes its MOD 2 FSC (Flash Suppressing Compensator).
The PWS MK1 Mod 2’s internals are unique. The rifle’s proprietary gas pistol system is attached to the bolt carrier group, somewhat similar to the AK system. The company claims the system reduces carrier tilt. Makes sense to me. The piston is physically is attached to the bolt carrier group; there’s no way for it to tilt.
I followed PWS’s instructions for breaking in the rifle. I fired a five-round group and immediately cleaned the bore. I repeated the process several times until I achieved consistent grouping. I zeroed my Trijicon MRO and quickly achieved half inch groups from a prone, non-supported position shooting at 25 and 50 yards.
To put the rifle through its paces, I shot it during my Night Combat rifle course. Over eight hours, in sandy and hot conditions I put around 350 rounds through the rifle. Over the next three weeks I fired another 1000 rounds down range. There were zero issues.
The rifle’s ambidextrous features were especially useful for support side shooting and manipulations. When flipping the safety selector to fire, the selector on the opposite would catch on my hand. I had to loosen my grip to flip safety and then regrip to reacquire it.
The PWS’ BCM butt stock was perfectly judged; it was the right width for my cheek without being too bulky. The rail scales came in especially handy (pun intended) for maintaining my grip on the rifle in the hot Texas weather.
The slim PicMod rail system makes it easy to get a sturdy support hand grip. It also eliminates the need to mount rails on the handguard to attach non-key mods accessories.
The rifle’s recoil was soft and easily managed. Whether it was down to the flash suppressing compensator or PWS’ gas piston set up, I found I could rapidly and accurately fire at targets both near and far without losing cadence.
The flash suppressor didn’t seem to make a big difference during the night shooting. In fact, I couldn’t tell the difference between shooting the MK116 or another AR with a standard bird cage compensator.
The PWS shot its best group from a supported bench rest position using Federal .223 69 gr Sierra Match King. I shot a .753 MOA group at 100 yards. Other groups shot were as follows:
- IMI 5.56mm OTM 77gr – .942 MOA
- Hornady .223 ELD 73gr – 1.394 MOA
- IMI M855 – 1.845 MOA
- Wolf Gold .223 55gr – 2.427 MOA
At the end of the day, some AR’s are more equal than other. I reckon the PWS’ ambi features, light recoil, PicMod rail and overall quality are worth the extra money.
Primary Weapons Systems MK1 Mod 2 MK116 AR15
Caliber: .223 Wylde – available in 300BLK
Length: 33 inches
Barrel Length: 16.1 inches
Barrel Twist: 1:8
Gas system: Piston – Mid Length
Weight: 6lbs 7.7 ounces
MSRP: $2049.95
RATINGS (out of five stars):
Reliability * * * * *
Zero issues with the rifle in dusty and hot conditions with over 1,300 rounds through it.
Accuracy * * * * *
Extremely accurate with the right ammo. The pricing on the rifle matches the sub MOA grouping.
Aesthetics * * * * *
A well designed rifle with a modest yet tasteful design on the upper receiver.
Ergonomics * * * *
The rail scales, slim rail, and BCM furnishing made it a comfortable and easy to shoot. Ambidextrous features are nice, but the safety selector is somewhat uncomfortable.
Overall * * * * *
You get what you pay for: a high-quality AR with little features that make all the difference.
I’m a little surprised they used a 1:8 twist; I’d thought 1:7 was now fairly standard for supporting the heavier range of ar ammo.
I haven’t shot one of their piston models, but I am rather fond of their “Modern Musket” DI ARs.
1:8 is becoming the de facto standard for civilian ARs because it can shoot everything that fits in a magazine, from 40 grains all the way to 77.
Once you shoot (and then clean) a piston driven AR, you will not want to go back to DI systems. I’m a left handed shooter and I’ve never had gas in my face (even when using a suppressor).
NOTE: Not all piston gas systems are quality built.
Piston driven ARs run so much cleaner, have better reliability (when using quality piston systems such as PWS, Faxon ARAK, and Custom AR firearms that use the Superlative Arms Gas piston driven firearms. I currently own a custom built (by myself) Superlative Arms Gas piston rifle. Zero malfunctions (thousands of rounds) with all three of these piston system ARs.
Of these 3, I would chose the Superlative Arms version due to it’s much lighter overall weight (5.5lbs without optic), simple (but robust) design, and better overall ability to fine tune your rifle’s gas system for optimum operation.
223 Wylde chambered 1:8 twist is the ideal choice for 223-5.56 ARs.
While the PWS muzzle device is nice, I much prefer the results when using the VG6 Precision Gamma 556. Slightly more overpressure to the side, but almost ZERO recoil and the barrel doesn’t rise/drop/shift left or right, thus allowing for instant follow up shots.
Forget the ZEV trigger (In my opiion it is not worth the money).
Instead try out a TriggerTech (3 models: Combat (5.5lbs), Competitve (3.5lbs) or the Adjustable (2.5-5.0lbs). The TriggerTech has the best trigger break and a super short reset.
Another great trigger option is the KE Arms SLT-1 trigger (4.5lbs). The design of the SLT-1 allows for the safety selector to be put in SAFE without the hammer being cocked and eliminates the standard design disconnector.
Of Note: The spring inside of the PWS bolt is not to help keep the bolt engaged with the barrel lug as stated in this article. The design purpose of this spring is to keep the bolt forward as the bolt carrier is driven reward. There are no gas piston rings in the PWS. By this spring keeping the bolt carrier forward, it helps to eliminate wear to the upper receiver by the cam pin. I use the POF Roller Cam pin on my AR bolt carrier groups.
Looking at that BCG arrangement, I can’t help but wonder how the dickens you get the BCG out of the gun while it is bolted to the piston. Could you give me a hint?
I own a PWS upper. Getting the BCG in and out is a little tricky, but not overly so.
The hardest part is you have to insert the BCG, the piston, and the charging handle into the upper as one assembly. It is more difficult than a normal BCG, no argument there, and you have to make sure the mating between the BCG and piston stays true, but it’s not rocket science.
So long story short, insert BCG into charging handle, mate up with piston, begin insertion into upper at a slight angle, seat charging handle, complete insertion.
Ron Grobman: The spring inside of the PWS bolt is not to help keep the bolt engaged with the barrel lug as stated in this article. The design purpose of this spring is to keep the bolt forward as the bolt carrier is driven reward. There are no gas piston rings in the PWS. By this spring keeping the bolt carrier forward, it helps to eliminate wear to the upper receiver by the cam pin. I use the POF Roller Cam pin on my AR bolt carrier groups
LarryinTX: The BCG assembly are removed the same as all other ARs. Look up some PWS disassembly videos on YouTube.
No one of consequence: Once you shoot (and then clean) a piston driven AR, you will not want to go back to DI systems. I’m a left handed shooter and I’ve never had gas in my face (even when using a suppressor).
NOTE: Not all piston gas systems are quality built.
Piston driven ARs run so much cleaner, have better reliability (when using quality piston systems such as PWS, Faxon ARAK, and Custom AR firearms that use the Superlative Arms Gas piston driven firearms. I currently own a custom built (by myself) Superlative Arms Gas piston rifle. Zero malfunctions (thousands of rounds) with all three of these piston system ARs.
Of these 3, I would chose the Superlative Arms version due to it’s much lighter overall weight (5.5lbs without optic), simple (but robust) design, and better overall ability to fine tune your rifle’s gas system for optimum operation.
223 Wylde chambered 1:8 twist is the ideal choice for 223-5.56 ARs.
While the PWS muzzle device is nice, I much prefer the results when using the VG6 Precision Gamma 556. Slightly more overpressure to the side, but almost ZERO recoil and the barrel doesn’t rise/drop/shift left or right, thus allowing for instant follow up shots.
Forget the ZEV trigger (In my opiion it is not worth the money).
Instead try out a TriggerTech (3 models: Combat (5.5lbs), Competitve (3.5lbs) or the Adjustable (2.5-5.0lbs). The TriggerTech has the best trigger break and a super short reset.
Another great trigger option is the KE Arms SLT-1 trigger (4.5lbs). The design of the SLT-1 allows for the safety selector to be put in SAFE without the hammer being cocked and eliminates the standard design disconnector.
I agree re the TriggerTech triggers … but I do have a gripe about them.
After dropping one into my favorite AR, it first became my even more favoriter AR for about five minutes. Then my wife tried it, and it became her AR. Dang trigger … I liked that gun. 🙂
Look on the bright side … she has an AR and now you get to build or purchase a new AR of your choice.
If you need a new Trigger Tech trigger be sure to look up Maligator Tactical (Florida). They are one of the top stocking Trigger Tech dealers here in the USA.
Also, if you haven’t tried one yet, the flat trigger bow option is outstanding on the Trigger Techs.
That looks like an ambi bolt release but not an ambi bolt catch like LMT/PDQ/ADM.
5 clicks to arrive at this article from the last one.
Please restore the next/previous article buttons.
Respectfully, another RF
What’s the point of a co-witness sight if you’re gonna throw a scope on top and a flashlight / your thumb in front of it?
Also, what’s the point of holding a rifle all outstretched like a seven-foot spear if there’s no bayonet? It looks dumb as hell, slows your target acquisition by widening your turning radius, and exposes your status as a weekend warrior because nobody I’ve ever known from any service branch has ever been trained to shoot that way.
I have a PWS MK 116 in 300 BLK. I shoot it suppressed and there is much less gas blowback than any suppressed DI platform I have shot. I have not, however, had the opportunity to shoot a suppressed DI platform in 300 BLK. It has a Geissele SSC trigger with straight bow. Recoil is more of a push than a jolt. I have zero complaints and can see no reason to ever replace it.
What’s you guys think of Adam Arms evo gas piston uppers.
I’d be really interested to see a version of this where you can fold the stock and still have a functioning rifle. I love the concept but for me not being able to fold the stock and fire kills it. Hopefully they’ll continue to innovate!
What does it say on the fasteners on the BCG? I’m trying to make sure they arn’t Chinese YFS fasteners like they suposedly used a while back. Any help would be most welcome,Sam.
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