Can someone tell me the main differences between the PWS piston system versus the Adcor Elite piston ?

They seem very similar.

Is there any problem with either system ?

Not sure about the other, but my PWS has run flawlessly with a 7-1/2" barrel in 7.62x39.  Very soft shooting gun and surprisingly accurate for such a short barrel.

I don't think you can go wrong with either system.

Both have excellent reputations.

I have a PWS MK114 and it is great. I had two but a friend talked me out of one and another shot mine, a SCAR 16 and 17 owner and promptly ordered one then after shooting it ordered another (Just in case the AWB is renewed he wanted a second).

Wulfmann

No real problems with either system that I'm aware of.

PWS is the closest to an AK "long stroke" piston, wherein the entire piston is attached to the BCG.  It is a low pressure/high volume setup that uses high volume of gas at lower pressures to operate the piston, whereas the BEAR Elite is almost a hybrid of the long stroke system.  It is a high pressure/low volume setup that operates the short stroke piston or "knocker" that in turn, pushes the op-rod and moves the BCG.  I say it's almost a hybrid because the op-rod is attached to the BCG unlike any other short stroke piston systems out there.  I have the BEAR Elite and am a big fan of the forward charging handle, ejection port wiper, and FN CHF barrel.  That being said, however, PWS and LWRC are the only other piston options I would consider getting if I were to get another piston gun.  

Hope that clears some of it up for you.

They are very similar, but not the same.  I'll try to give a basic description, and if I don't get something quite right, I'm sure someone will clarify.  I don't claim to be an expert, just another enthusiast.

The PWS uses a true "long stroke" system, where the piston is attached directly to the bolt carrier by means of an operating rod.

The Adcor uses a hybrid short/long stroke.  The actual piston is not attached to the op. rod, and impinges only momentarily on the end of the rod.

I prefer the PWS system because it most closely matches the tried-and-true AK-47 style of action, with all the ergonomic benefits of the AR.  I've read that this action has a longer dwell time, which helps cycle the action more smoothly.  As I perceive it, the gas has more time to "push" the piston/op rod/carrier assembly before the excess is bled-off through the vents in the op. rod sleeve.  This set-up also helps keep the BCG in a straight line, thus avoiding the infamous "carrier tilt disease" that infected some first gen. short-stroke designs.

The Adcore is more like a short-stroke system that uses a permanently attached op. rod to avoid the carrier tilt. Almost every other short-stroke has a separate op rod that slams into a "strike-face" on top of the carrier.  Adcore attaches this op rod to the carrier, similar to the PWS. but the piston still slams into the end of the op rod, unlike the PWS.  I don't like all this "slamming" going on.  I'm no engineer, and there are lots of very respected companies, with real engineers, that swear by the short stroke system. It is certainly the dominant design out there.

I just don't like it.  Why have steel slamming on steel when it's not necessary?  Why add a bunch of springs to the hottest, most active part of the gun?  

The PWS design just seems like the simplest, most logical, and least likely to malfunction.  For the life of me, I have no idea why they are the only ones using this design.  (If you don't count the dozens of foreign militaries fielding millions of AK's that have been going strong for over half a century now.)

This is just one man's opinion.  Your's may differ.  Keep in mind that there's nothing "wrong" with either system.  There's nothing "wrong" with the original DI system either.  I just wanted something that I could run lots of cheap, dirty ammo through and not have to spend more time cleaning than shooting.  If accuracy is most important...you should get a DI system.

Do some more research and pick the design that makes the most sense to you.  That's what I did when I ordered my first PWS.  I'm so satisfied with my decision that I just ordered two more uppers that should be here next week!  After that, the rest will be DI...

ETA:someone beat me to it.  serves me right for walking away before i hit send

The Adcor Bear is a free float system (barrel and handguard...), the PWS is not. The Adcor's free float barrel aids in accuracy and it's design (titanium op rod, alloys, etc...) keeps the weight down. The non-recipricating ambedextrous forward charging handle also sets it apart from the rest. It is also one of the few rifles being evaluated as a replacement for the Army's current M4 carbine. The PWS is a fine rifle built much like the Sig 556 or the AK. It would be great if you could shoot both and make your own decision.


-Mike

I love the PWS piston system but would love if I could use aftermarket third party handguards.

The bases for the ADCOR rifles and PWS rifles have pretty much been covered. I personally recommend ADCOR because I like the forward charging handle and tool-less design. I've had mine over a year and I still love it like when it was new. A lot of my friends who have shot it loved it and wanted to know where to get one. Most people love the thing when they are just finger banging it.

I do suggest your try them both. Stock off the bat the ADCOR is more friendly for left handed people such as myself.













This is an older pic of it before some of the other stuff I did to it: