Next Evolution of the Piston AR: Primary Weapons Systems Mk116 Mod 2

PWS has taken its concept of the AR rifle another step forward with its next generation MK1 (M16/AR-15) and MK2 (SR-25/AR-10) series of long-stroke piston ARs. PWS literature clearly lays out the thought process behind the development of its ARs: the appreciation of AK simplicity and reliability combined with deep-rooted experience with M4/M16 ergonomics.

PWS is confident its long-stroke piston-operated AR is an improvement over not only the original gas-impingement design, especially when incorporated into short-barreled platforms, but also other piston AR designs featuring short-stroke pistons.

THE PWS DIFFERENCE(S)

Significant differences are present in the MK1 PWS compared to both the direct-impingement operating system and other piston-driven operating systems. PWS product improvements address reliability and performance issues as well as reduced carrier tilt, cam-pin wear, and carrier bounce.

Proponents of piston-driven ARs point to greater reliability in adverse conditions and less reliance on routine maintenance compared to the direct-impingement operating method.

The increasing use of suppressors for private citizens, law enforcement and military highlights another advantage of piston-driven ARs—the ability to adjust the amount of gas siphoned to operate the action.

Suppressor use increases operating pressures a considerable amount, so being able to turn down the gas vented to the operating rod just by quickly turning a knob is a big advantage.

Piston-driven ARs also enjoy a perception of better operating reliability in harsh environments, especially as barrel lengths shrink. The PWS MK1 series represents cutting-edge long-stroke AR design. This is different than the original Stoner-designed gas impingement design as well as the growing numbers of short-stroke piston ARs on the market.

The PWS long-stroke piston evolved out of early PWS short-stroke conversions by eyeing simplicity and fewer, hardier parts. Proponents of the long-stroke AR method argue it does not have multiple parts banging into each other with the operating rod and bolt carrier group moving together under the impulse of a fired round.

This contributes to minimizing the carrier tilt and carrier bounce found on short-stroke AR piston designs. The PWS MK1 requires no tools for disassembly and needs less maintenance than other piston systems.

PWS added a new Ratchet-Lock Design to eliminate the need to stake the castle nut. The Ratchet Lock gives a rock-solid lock-up while being able to be removed easily if needed. An extended lip on the buffer tube eliminates carrier tilt. An extended BCM charging handle offers the user plenty of purchase to operate the MK116’s bolt group.

PWS’s Stacey Nagy indicates a main impetus to the evolving PWS MK1 and MK2 series was the need to adapt to increased suppressor use by military, law enforcement, and private citizens. PWS responded to the obvious need for a simple gas-block adjustment.

A PWS-provided tool stored in the pistol grip inserts into the adjustment holes in the gas knob. Simply rotate it to the next position/detent until the desired setting is selected for your specific suppressor set-up.

An adverse-condition setting is not needed, as the PWS system is designed to operate with enough back pressure at all times no matter how dirty or fouled. That is something to appreciate in a fighting rifle.

.300 BLK

The PWS rifles chambered in .300 BLK are even simpler. PWS research and product development with the .300 BLK have shown it does not need the gas adjustment system as found on .223/5.56 chamberings. The .300 BLK MK116 is meant to run with a can or without, with supersonic or subsonic ammunition, with no gas adjustment required.

What distinguishes the .300 BLK is its ability to access standard supersonic rounds for typical longer-range engagements superior to 5.56mm while maintaining a trump card of subsonic ammunition for more discrete specialized work. The .300 BLK was created in response to a U.S. military Special Operations force’s request.

Literature illuminates their goal with the .300 BLK being the ability to launch .30-caliber projectiles from the AR platform from existing 5.56mm magazines without a reduction in magazine capacity or reliable functioning. Another notable characteristic of the .300 BLK is its compatibility with the AR standard bolt, thus only a barrel change is necessary.

At 300 meters, the .300 BLK has approximately 17% more energy than the 7.62x39mm. From a nine-inch barrel, the .300 BLK has the same energy at the muzzle as a 14.5-inch barreled 5.56mm M4 and surpasses it as ranges extend.

Hornady, SIG Sauer, and Black Hills .300 BLK loads were chronographed. The supersonic loads clocked between 2,210 and 2,395 feet-per-second (fps), with the subsonic loads measuring 990 to 1,005 fps.

Accuracy from the .300 BLK barrel was a pleasant surprise. Other .300 BLK rifles I’d tested generated less than stellar consistency, with certain loads favored greatly over others. This was not the case with the MK116. No load tested, whether supersonic or subsonic, produced greater than 1.75-inch average accuracy at 100 yards after firing three five-round groups.

TRIJICON VCOG

This accuracy level justifies leaving a magnified optic such as the versatile Trijicon VCOG 1-6X mounted on the MK116. The Trijicon VCOG (Variable Combat Optical Gunsight) 1-6X with Illuminated Reticle is designed for both instinctive close-range/low-magnification situations with variable-intensity red illuminated reticle, yet still allows shooters to engage targets with greater precision at longer ranges thanks to the 6X.

Combat experiences in Africa and the Middle East served as the catalyst for new optic types such as the Trijicon VCOG compared to only non-magnified red dot or fixed-power magnified optics. The VCOG is worthy of consideration for anyone as it enhances rifle performance.

This displayed the PWS rifle’s potent firepower and combat accuracy. Firing from unorthodox positions while working around range vehicles showed why the lightweight seven-pound MK116 is such an effective combination, with the .300 BLK a nice upgrade in firepower.

Over 600 rounds of subsonic and supersonic ammunition were fired with the MK116. The .300 BLK subsonic loads had no issue cycling the rifle, even when firing without a suppressor attached.

The advantage of having a .300 BLK rifle like the PWS MK116 functioning with subsonic loads unsuppressed means a user can be confident of having a working weapon no matter what ammunition is used.

Firing the PWS MK116 from the prone position produced consistent hits out to 250 to 300 yards on steel targets placed in and around range vehicles. The Trijicon VCOG’s crisp image aided in spotting the targets in the vehicles’ interiors, with accurate fire then placed.