Primary Weapons Systems first introduced the MK116 MOD 1-P and MOD 2 in both .223 Wylde and .300 Blackout. Then PWS decided to change up the game a bit by offering both a rifle and pistol chambered in 7.62×39 Russian. Many in the industry have tried this amazing feat and failed. PWS has not only done it, but done it right.

Both the MK116 MOD 1-P and MOD 2 in x39 (7.62×39) are offered in various configurations from the factory. You can purchase it as a complete 16-inch rifle or simply just the upper receiver. One can even purchase the upper as a MK1 MOD-2. A pistol variant is also available in either an 11.85 inches or 7.75 inches. Or you can go apply to the BATFE and make it an SBR. PWS refers to its 7.75-inch x39 variant as the “Diablo.” After extensive shooting of that demon, I can see why.

Beast of a Rifle

PWS is unique and has its own niche in the AR marketplace. This is largely in part due to its proprietary long stroke piston design and three-position adjustable gas block. The best way to describe it is that the PWS long stroke piston mimics the piston design of the legendary AKM series of rifles.

Most, if not all of the AR piston variants offered on the market today, are a short stroke piston design. You will not find any of the dreaded “carrier tilt” or piston slapping in the PWS that have been common in some of its short stroke piston cousins. This is due to the way the long stroke gas piston is designed to move, as a unit rather than several moving parts that are slamming around.
Now, before anyone’s feelings get hurt, I’m not knocking the short stroke piston design. When done properly, it too is an amazing system.

PWS hit this one out of the park though with the MK116 MOD 2. It features a sleek design with lightning cuts in the receiver to help reduce weight. It also lacks a forward assist. Most users will have to add rail sections to a KeyMod or MLOK equipped upper receiver in order to use a pic rail accessory. Not so in the case of the MK1 MOD 2, as it’s equipped with what PWS calls their PicMod rail system. The PicMod rails allow for both Pic rail and KeyMod accessories to be utilized without needing additional hardware.

PWS MK116 MOD 2 Features

This rifle being an older example, PWS is now offering what they call “PicLok,” to work with both Picatinny rails and M-Lok compatible accessories. PWS even machined a trunnion into the upper receiver for a “superior fit.” Tons of attention to detail went into this rifle.

The lower receiver is also an amazing design, especially if you’re a Southpaw like myself. The controls are completely ambidextrous, that includes the safety, bolt & mag releases. It’s quipped with the new PWS Enhanced Buffer Tube (EBT). This is a truly innovative design in itself. The EBT has 6 positions for the stock to be placed in, along with lightning cuts to reduce weight. The castle nut is a ratcheting design so as to be easier to remove if needed. There’s no need to stake your castle nut with this design.

It also features a central QD sling attachment for an end plate. But the icing on this cake is the trigger. It’s what ZEV Technologies calls the SSR (Single Stage Rifle) trigger. Yes, you heard that right, ZEV is now making rifle triggers. If anyone is not familiar with Zev Technologies, they make shooting handguns that much better with the addition of their aftermarket parts. Their claim is that it “bridges the gap between the multitude of two stage triggers intended for duty use, and single stage competition triggers.” The model that I tested came equipped with a 5.5-pound trigger pull that had an icicle like break. Personally, I feel that poundage is a sweet spot for trigger pull weights. One can always opt for a ZEV 3.5-pound spring though. At 5.5 pounds, it’s perfect for home defense, range use, or even as a police patrol rifle.

Sights and Dots

Sights are an integral part of any firearm. When it comes to back up iron sights (BUIS), the Diamondhead “Diamond Integrated Sighting System is a great setup. Too many people discount or dismiss altogether a good set of BUIS. Iron sights never run out of batteries, and can be good for hundreds of yards, depending upon the shooter.

As for red dots, the Trijicon MRO Patrol is amazing for its intended use. The supplied ARD Kill Flash I found to be a bit over the top though. Kill Flashes are great and all, but I’ve never liked them on red dots. Personally, I’m not too worried about a forward-facing glare at close distances. On a variable powered scope, then absolutely, add one on.

With a total of 10 brightness settings and a 5-year battery life, The Trijicon MRO Patrol is a serious contender. It’s the perfect medium between a full-size red dot and a microdot. Using my Google-Fu, I found that Primary Arms is offering them for $550 with a 1/3 co-witness quick release mount. That’s a very reasonable price. I’ve always lived by the old saying “buy once, cry once.”

Range Impressions

In trying to be impartial, five different types of ammunition were tested. Giving readers a wider variety of testing results helps to make you better informed. From ball “range” ammo to Hornady SSTs, the MK 116 MOD 2 shined like a diamond.

I won’t get into the whole AK vs. AR debate as I sit on the fence with one foot over on the AK side myself. Both types of rifles have their advantages and disadvantages. What PWS did was make an upper receiver in x39 capable of mounting to an existing 5.56 lower receiver with no modifications what-so-ever. All one needs is the specific mags that will insert into a standard 5.56 “mil-spec” lower.

In the grand scheme of things, the ASC 30 round 7.62×39 AR mags aren’t all that expensive. A quick search netted me several different vendors selling them for $18.99 each. That’s less than what it costs for a premium AK mag. In the past, many manufacturers have had issues with these types of mags if they load them all the way to 30. I didn’t try that as I don’t load my mags to full capacity. I loaded these to between 25-28 rounds each and found that with the exception of one of the mags, the ASC 30 rounder’s preformed without issue.

For accuracy testing, that consisted of using a Caldwell Lead Sled DFT 2 and Stable Table Lite for best 100-yard groupings. Using Hornady SST 123 grain V-Max choice of round, I was able to net a .64 MOA five round grouping at 100 yards. Mother Nature cooperating with beautiful weather and absolutely no wind certainly helped.

Bottom Line

The recoil impulse was minimal and actually felt pretty soft. The PWS MK 116 MOD 2 was a very comfortable rifle to shoot. Perhaps that’s due in part to coming factory equipped with a Bravo Company Manufacturing grip and stock. BCM is known for putting out high quality weapons accessories. So it’s a no brainer as to why PWS chose the furniture that they did.

The MK116 MOD 2 balanced very well and weighed in at around 6.5 pounds according to my scale. There goes the argument about piston driven AR’s weighing more than their direct impingement brethren. However, with all of that being said, it would be interesting to see PWS offer this upper with a modified lower that accepts standard AKM magazines — imagine those possibilities.
It was a natural feel when aiming the MK116 MOD 2. Everything about shooting this rifle put a smile on my face. I had my son and daughter shoot this rifle and their thoughts were matched up to mine. Trying to be objective, watching my daughter shoot this rifle was a hoot. If a female who is 5-feet tall and 115 pounds soaking wet can manage good shots on target with this rifle (standing unsupported), then I have nothing but respect for it.

If you’re looking for a nice alternative to owning an AK, this is definitely it. One can own a single lower receiver and use not only the PWS 7.62×39 upper, but any standard AR compatible upper receiver in your favorite caliber. I’d have to call the PWS MK116 a sure winner that should more than meet your range and home defense needs.

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PWS MK116 MOD 2 Specifications

  • 16.1” barreled upper with Flash Suppressing Compensator (FSC) (7.62×39 Russian) with a 1.10 twist
  • Overall Length (OAL) 33”
  • Piston System: Mid-length Long Stroke Gas Piston System
  • Weight (minus BUIS and optic): 6.5 pounds
  • Trigger: Zev-Tech Custom AR Single Stage Trigger
  • Optic: Trijicon MRO Patrol
  • BUIS: Diamondhead Integrated Sighting System Back Up Iron Sights

PWS MK116 MOD 2 Accuracy Results

  • Wolf (Green Box) 123-grain HP: 2,270 fps, .82 MOA
  • Golden Bear 125-grain SP: 2,332 fps, 1.6 MOA
  • Red Army Standard 122-grain FMJ: 2,291 fps, .86 MOA
  • Golden Tiger 124-grain FMJBT: 2,202 fps, 1.5 MOA
  • Tula 8M3 124-grain HP: 2,444 fps, .69 MOA
  • Hornady SST 123-grain SST HP: 2,141 fps, .64 MOA

Bullet weight measured in grains, velocity in fps by Cladwell G2 Ballistic Precision Chronograph at 20 feet, and accuracy in inches for best five-shot groupings at 100 yards from a seated bench rest (Caldwell Stable Table Lite) using a Caldwell Lead Sled DFT 2. Rifle topped with a Vortex Razor HDII 1-6×24 scope. 


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