PWS Diablo 7.62x39mm

The 7.62x39mm PWS Diablo upper receiver worked well with the…

The 7.62x39mm PWS Diablo upper receiver worked well with the author’s registered SBR lower, providing compact yet capable firepower. Note the small size of the SBR with its short 7” barrel and collapsed stock.

I am always on the lookout for weapons chambered in the 7.62x39mm round. As much as the ergonomics of the AR-15 suit me, the 5.56mm cartridge has never been a preference, but getting AR platform rifles to work well has been a bit problematic. Given a military application the preference would be the 7.62x51mm, but in the law enforcement world, especially for entry, it has not caught on because of liabilities and perception issues. Any weapon a police officer uses will be scrutinized heavily and changes have to be made carefully. Quite often it is less about the weapon or the cartridge, but how it looks. It is one of the reasons the AK47, especially in its standard form, has not been widely adopted. Fortunately that is changing to a degree, mostly because the firearms world is doing all it can to make the AK47 look like an AR-15.

The 7.62x39mm offers a number of advantages, especially since it has much less of an image problem than the the AK47. The 7.62x39mm is a bigger bullet with a solid velocity, and the proper projectile has proven to be a good manstopper. There are no surprises with the round, and it has proven itself for decades in every corner of the world.  Until the recent paranoia, it was prevalent and very economical, manufactured in huge quantities all over the world with mil-surplus ammunition plentiful. Although certainly not a bargain anymore, it is still less money than many of the NATO cartridges.

AR-15 Solution

pws-diablo-762x39mm-bThe CQB compensator, made by PWS, is intended to make the system run more efficiently and provide sufficient backpressure.

The solution is the manufacture of an AR-platform rifle that uses the 7.62x39mm cartridge. It was simpler to envision than to make it reality, especially with the gas impingement systems. There have certainly been more than a few out there starting with Colt many years ago, which still has following to this day. Several other companies are making and have made uppers in that caliber as well. Most of these worked pretty well with the primary issue being the magazines. With a good magazine these rifles worked pretty well, at least as well as any AR-15 did at the time.

The next step in the evolution was to build one in a piston driven platform. It only seems fitting, since most of the piston driven guns out there are some variation of an AK47 action. There have been a few over the years, but the market was just not there and they were never widespread. There was also the ever-recurring issue with the magazine. Even with the problems there were always a few out there clamoring for an AR-15 in 7.62x39mm that worked.

That clamoring has grown as of late and become a more popular idea. Some were asking for a short-barreled upper. The cartridge lends itself to close-up work and seems to lose far less velocity when the barrel is shortened when compared to the 5.56mm. You are still right at 2,000 fps (feet per second) with a 120-grain bullet in a 7-inch barrel. It is just about a perfect weapon for entry, or executive protection. Well, it seems that Primary Weapons Systems has listened, as they now have an SBR Diablo in 7.62x39mm.

Upper Details
pws-2The Picatinny rail forend of the Diablo extends to the muzzle device, offering the longest sight radius possible for the folding iron sights.

Having tested several of their uppers, PWS builds some of the best quality receivers available. The workmanship is first rate, the quality control is solid, and quite frankly I have never had one that did not work. When the Diablo arrived there was no disappointment. The receiver is a VLTOR MUR-1 and mated to the PWS forend nicely. It uses the CQB compensator seen on all Diablo’s receivers. The barrels are stainless steel with a polygonal bore. The bolt is also stainless and a billet machined charging handle is used. To ensure trouble free operation the internals are all coated with QPQ, a super hard coating that not only makes the parts last longer, but has a natural lubricity making them resistant to operational issues due to fouling. The bottom line here is — it is quality and often at a retail price point at or lower than the competition. It is one of the things I really like about this company. The upper comes with one 10-shot C-magazine and enough rail panels to cover the rail as you see fit.

For this test a new buffer tube, tungsten buffer and spring was provided. This was something PWS introduced recently and has become quite the hit. More than just another buffer tube, there is quite a bit of innovation here. It is machined from a solid piece of 7075 aluminum and has six positions. This eliminates the castle nut and places QD sling swivels on the tube. Out of the box, it allows a single-point on either side without anything hanging out to catch your knuckles on. It has the added bonus of allowing the stock to close all the way, something other systems prevented. The tube extends over the retaining pin, making it impossible for it to come loose.

Another innovation is the dead blow buffer installed in the rear of tube to reduce carrier speed. This is critical for a rifle that is suppressed or has a short barrel. The buffer is a Spike’s Tactical machined from solid bar stock and filled with Tungsten instead of weights. It is designed to smooth out the recoil. Coupled with the buffer tube the difference was rather striking.

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