The debate has raged for years: AR-15 or AK-47. Precision or reliability, direct impingement (DI) or piston, 5.56 NATO or .223 Remington. Usually the process of choosing a “perfect” rifle for competition, self defense or even hunting is filled with compromises that need to be weighed in order to determine which tool fits the job best. But not with PWS’s line of rifles . . .
The AR-15 market is about as diverse as a redhead convention in Finland. Some might use a different bolt carrier here or a new handguard system there, but very few actually offer legitimate “improvements” over the basic design that Eugene Stoner came up with more than 50 years ago. The PWS MK 114, however, features one very legitimate improvement that puts their rifle ahead of the competition: the operating system.
There are an ever increasing number of AR-15 rifles on the market that use a gas-piston system instead of the traditional gas-expansion/direct-impingement arrangement that Stoner designed, but almost all of them, from Adams Arms to LWRC, use a short-stroke piston instead of a long-stroke piston system. The piston guns’short-stroke method means the operating rod only acts on the bolt carrier for a short period of time and imparts all of the force on a small strike face at the top of the bolt carrier (where the gas key usually is).
The problem is that the AR-15 was designed to have all the force in the bolt carrier centered, with the bolt acting like a gas piston itself and keeping all of the forces roughly in-line with the direction of travel. By having the force applied off center in this way, the bolt has a significant amount of “carrier tilt” where the back of the bolt carrier will constantly be rubbing against the bottom of the buffer tube. It’s not ideal, and over time it can lead to excessive wear on your gun.
The beauty of the PWS design is that it’s a long-stroke system, meaning that the long piston is directly attached to the bolt carrier group and extends all the way to the gas block. The longer piston means that the rotational force applied to the bolt carrier is significantly reduced, and as a result there’s almost no carrier tilt. The gas tube along the barrel provides a guide for the piston and keeps everything straight as the gun cycles — exactly the same as the piston system in the AK-47.
In order to make the gas system work with standard charging handles, Primary Weapon Systems designed the operating rod to be segmented instead of a single solid rod. The front section is slotted onto the bolt carrier, and can be detached to slide the charging handle of your choice onto the bolt carrier assembly before inserting the whole thing into the receiver. It’s a touch more difficult than the normal AR-15 reassembly process, but it’s very straightforward.
One of the side benefits of a piston system like PWS uses is that you also get an adjustable gas port. Normally in an AR-15 the gas expansion system is self regulating (to a point) and will continue to function even with inconsistent ammunition. But with the PWS gas system, you can adjust the amount of gas being bled off from the barrel and tune the system so that you have just enough energy to cycle the action. A properly tuned gas system means less excess energy being transmitted to the shooter, and therefore less felt recoil. Add in the extra reciprocating mass of the piston and the rifle gets very gentle.
Adjustable gas block systems also mean that you can get improved reliability in those situations where the shooter’s comfort is a secondary concern — like a battlefield. If you’re in a dirty environment, you can turn up the gas system and more energy will be siphoned off from the gasses in the barrel, leading to faster cycle times and better reliability. You don’t even need to whip out the tool kit to make that change: the tip of a 5.56 caliber bullet will let you make the adjustment just fine.
PWS could have stopped with the improved operating system and called it a day. It’s the best piston system available on the market, and might even have given Stoner a moment of pause if he’d seen it. Instead they decided to kit out the gun with some custom parts that use some of the best technology available.
First up is the most noticeable original part: the muzzle brake. PWS’ FSC556 is one of the best there is, and as a result it’s used on many manufacturers’ guns, not just PWS’s. FNH USA, for example, chose that muzzle brake for their SCAR series of rifles. The reason is pretty clear when you get the gun on the range, as it’s an efficient design that works really well.
Another improvement is the buffer tube (or “receiver extension tube” for you semantic pedants). PWS uses their own CNC machined buffer tube that doesn’t need a castle nut (and so won’t walk itself out of position), has some QD mounts built in for added convenience, and has an extra lip on the front that helps eliminate what little carrier tilt is left. The original design for the collapsible stock on an AR-15 was a hastily designed disaster, and PWS’ solution is one of the first that actually feels like someone sat down and thought about the problem for more than five minutes.
The last improvement is in the rail system. PWS uses a free floating barrel to improve accuracy and keep the handguards from heating up, which uses a full-length top Picatinny rail and a keymod attachment system that has become extremely popular lately for everything else. That allows the shooter to either attach individual rail sections where they need them or simply slot attachments directly into the keymod system, keeping the rest of the handguard flat and comfortable.
It also cuts down on weight and makes the rifle much more comfortable to shoot while giving up exactly nothing in terms of configuration. All of the high-end manufacturers from Accuracy International to Knight’s Armament have switched over to this system, and I expect it to be the industry standard for “tactical” AR-15 rifles in the next couple years.
Whatever parts PWS doesn’t manufacture, they source the top shelf versions available. Instead of a chintzy standard charging handle PWS uses the BCM Gunfighter charging handle. Instead of the standard spongy trigger is a QMS Mil Spec trigger, which I reviewed and use in my 300 BLK rifle. And for the iron sights, stock, and grip, PWS decided to run with the Magpul versions. In short, it’s a rifle kitted out exactly how I would kit out a “run-and-gun” rifle.
Out on the range, the gun performs superbly. It’s a dream to shoot, lightweight enough to transition smoothly from one target to the next while being solid enough to build bridges out of. Everything on the gun felt “right.” But before I passed judgment, there was one more test to complete: accuracy testing.
PWS custom machines their own barrels from blanks, and this barrel was no different. They use a 1:8 twist, imparted using a button rifling process (not the most accurate process, but good enough). The chamber for the .223 caliber projectiles is the increasingly popular .223 Wylde chamber, which combines the best features of the 5.56 NATO spec and .223 Remington to accommodate both types of ammunition while maintaining the best accuracy. And on the 100-yard range, it certainly looks like all that work paid off.
This five-round group was shot using bog-standard 55-grain Federal American Eagle .223 Remington ammunition, also known as “the cheap stuff.” But even though the ammo wasn’t the greatest, the rifle performed remarkably well. The horizontal dispersion of the group was about 1/2 inch center to center, and vertically the shot group was about 1 inch center to center. I went back and re-tested with some nice Winchester 55-grain ammunition and started getting bored with the 1/2 MoA groups I was getting with the rifle. I’d post a picture of those instead, but I think this group using the most common ammunition available is more impressive.
There is a small caveat: The gun didn’t like 77-grain ammunition for some reason. I think that the twist rate might not have been ideal for the heavier rounds, and I couldn’t get a good group with even match grade Federal Premium ammunition in that weight.
There are very few rifles that I actually like. PWS’s MK114 rifle is definitely one of them.
Specifications: PWS (Primary Weapons Systems) MK114 Rifle
Chamber: .223 Wylde
Barrel Length: 14.5 inches (pinned and welded flash hider)
Weight: 6 pounds, 9 ounces
Capacity: 30-round magazine
Features: PWS long-stroke piston operating system, three-setting adjustable gas system, forged upper receiver and lower receiver, included forward assist, FSC556 compensator, MLOK free-float handguard, 1:8 barrel twist rate, Bravo Company furniture, Radian Raptor Charging Handle, does not require NFA SBR paperwork, minimum recoil impulse, good for law enforcement, hunters, competition shooters, as well as everyday firearm users
RATINGS (out of five stars):
All ratings are relative compared to the other weapons in the gun’s category. Overall rating is not mathematically derived from the previous component ratings and encompasses all aspects of the firearm including those not discussed.
Accuracy: * * * *
1 MoA with standard 5.56 ammunition is nothing to sneeze at. 1/2 MoA with better ammo is excellent. But the lackluster performance with heavier bullet weights was disappointing.
Ergonomics: * * * * *
The rifle feels exactly how an AR-15 should.
Customization: * * * *
PWS rifles give you tons of options on how you want to set them up, from keymod attachments to QD cups and everything in between. But the long-stroke gas system limits your options when it comes to replacement bolt carriers.
Overall Rating: * * * * *
I honestly can’t remember the last time I gave anything a five-star review. But this rifle absolutely deserves every single star. A nicer trigger would be a welcome addition, but it works well as-is.
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