My PWS setups don’t have any of these issues. They balanced and shot suppressed better than my KAC SR-15 and SR-16 setups. My PWS Mk111 Mod 2 was actually lighter than my SR-16.

Honestly when there are options like PWS available today, there’s no need to go with a DI when looking at a full time suppressor host. PWS is just as light as DI, just as accurate and has the added benefit of its operating system.

The "too heavy" or "added weight" argument is more of a legacy argument for people who haven't really followed more recent piston system development.  Similar to the "carrier tilt" argument.  More recent piston systems (specifically the Superlative Arms system) add so little weight that simple choice of muzzle device can overshadow piston weight.  Similarly barrel profile far overshadows many piston systems for weight addition.  Case in point, if you take the piston hoody2shoez mentioned where the piston is 1.2 oz added weight.  Then put an A2 on the piston and a Surfire warcomp on the DI, the warcomp is 3.8 oz verse the A2 at 1.9oz.  You end up with a heavier DI gun than piston gun by 0.7oz, all other things being equal.  Anyway, my point is simply that there are SO many things people add or remove or change or alter about their own person rifle that the piston is certainly not adding THAT much weight.  I've dropped over a pound off one of my rifles simply by changing the barrel profile and using a different handguard.  

That said, manufactured piston rifles (as opposed to kit built) may see different results because they may be adding other things.

Have PWS piston guns gotten lighter? My buddy’s 14.5” is definitely heavier than any of the similar rifles in our group. Its actually a great gun, but the weight shows up on a shot timer, and its noticeable in use. Not always a bad thing, but definitely a thing.

A 416 is definitely heavier than equivalent DI carbines in SOF use. Up to about a pound of difference in same or similar barrel lengths, but thats not only because of the piston.

If a piston and oprod are heavier than a gas tube, then a piston gun of equal barrel contour and length, with as equal as possible rail, simply must be heavier. It might not be a big difference, but it is there.

I have PWS rifles. Hell, when I was contracting way back in the day we ran some of the first ones available. Since then I’ve used them competitively on occasion.

They’re good rifles, but they’re no more reliable under adverse conditions than a similar quality DI gun and they’re still heavier forward of the receiver. When you put it on the clock it’s noticeable.

Definitely neither more reliable, nor cleaner. With a Chimera, we’d have to turn the gas back up after it got dirty because of short-stroke stoppages.

In the 1940's we had the light weight intermediate power select fire firearm that had 30 round magazines.



Then we developed the superior 5.56 cartridge and DI gas system to run it - a major engineering technological improvement.
So:


But some people still wanted piston, for nostalgia and other reasons.



But people wanted it in AR15 configuration. So, we got piston configured AR15s.  And then people wanted cool exotic rounds.  Roudns like. - ZOMG,  .30 cal round!!  In a PIston.   Or basically...

 
But shaped to look like this.

While really, basically back to the 1940s of this, looking cooler:




Then people finally realized - you know, the DI gas system and the 5.56 round are actually pretty swell.


And look at that, 5.56 DI is still the standard issue GI rifle of the US Military, and will continue to be so, basically for the rest of our lives.

DI is being phased out of the military. Usmc has been switching to the m27 for some time now and the army's SPEAR will eventually take over as well.

How's that coming along?  That was announced how long ago? The USMC who have the shittiest budget of all the Armed Forces, are going to replace low cost M4's, with HK guns?  Really?  Got to love the Wikipedia page on this; it's so written by HK (or Larry Vickers), where the M4 is a 4-5MOA gun, but this gun is 2 MOA?  Who came up with that??   About the only place this gun actually makes sense is to replace worn out SAW's with these.  Which is basically all they've done.  Though, how a magazine fed piston driven M4 with short barrel = belt fed SAW for the same mission application;  I still haven't figured out.   But apparently that's the plan.

It's actually going quite well. They've refitted the entire infantry side below platoon leadership level. From what I've heard they eventually plan to replace every single rifle.

The mk18 is getting phased out in higher tier'ed units for the mcx in 300bo... another piston gun.

417's are used quite often as intermediate ranged options. Again another piston.

We've invested a lot into the development of DI. But DI is going to go the way of the 1911 I believe in the future.

There are, indeed, a lot of piston guns planned for and existing in US inventory, and most are heavier than their DI counterparts. Interesting thing about USMC is that MARSOC is still happy with suppressed Mk18s and M4s, and using a .30 for DMR, against big Corps going with HK all the things and big Army going with Sig all the things.

GWOT experience has flipped the table somehow, from conventional troops getting legacy DI guns (now somewhat modernized after extensive SOF testing) and SOF getting or wanting to get piston guns. And now its Opposite World where SOF’s got Noveskes, URGIs, Mk18s, and M4s, and conventional dudes are getting 416s, 417s, and that Sig atrocity.

You and I have different experiences it seems. I haven't seen any di's except for the occasional noveske and I haven't seen any sof dudes with mk18's. I'd love to hear more about your recent experiences as they vary greatly from mine

*edit*
I do see a lot of usmc recon rocking mk18's still but that's normal

I haven't worked directly with conventional forces in some time. I just know what I see and hear

I sadly have one of these POS's too. Attached File

Double post?

Also a piston/DI [ab]user - I think the most noticeable effect is when shooting suppressed, and even mores so with 7.62/308Win. The reduction in gas coming back into your face/eyes via the charging port is significant. There are mitigations for this, of course, with DI, but the PWS 308 I like to shoot suppressed has performed flawlessly. I don't have any practical piston experience beyond PWS rifles, so take my PoV with a grain of salt. I certainly wouldn't be tempted to build my own.

Obviously, it's heavy, but it's a large frame so I expect it. I'm one of the few, if only, people I know who hunt with (and by extension, carry) both.

These are the models for my basis that I own. I have hunted and killed white tail deer/coyote with all of them.

PWS MK216 Mod1-M 308Win
PWS MK116 Mod2-M 7.62x39
PWS MK111 Mod1-M 7.62x39
PWS MK111 Mod1-M 223Wylde

The reliability of the PWS 7.62x39 offering is astounding compared to every other DI AR chambered in x39 I've shot.

Honestly, if you like it, just shoot the damn thing. If you don't, sell it and let someone else shoot it. What a great country we live in when we can argue about the availability, pros and cons of gas systems in such a plethora of rifles and calibers!

That was a great post, and in particular, the concluding statement is spot on for sure, which we all can sometimes forget.  Shoot what brings you joy!

The PWS rifles that I have experience with are their Mod  2 variants. They are the lighter weight options. I think their pro line and Mod 1 is a bit heavier.

My PWS Mk111 Mod 2 was 1-2 oz lighter than my KAC SR15 CQB Mod 2 with same accessories setup on both.

PWS has found some black magic with their long stroke piston design. Suppressed, I haven’t found another AR15 platform that shoots as nice. Recoil wise it is as soft as a KAC if not slightly softer. It really is a very pleasant gun.

People can debate DI vs piston. It’s nice to have options. I own many of both variants. But for joy of shooting and lack of needing to do maintenance or cleaning, I’ll take the piston setups. They just do better ime.

I went the clone way; a mix of original plus cloned parts. Love it. Works flawless at half the price or less. Still my favorite.


US Mil Style HK416D by Solo__, on Flickr

Your boy probably has the now discontinued PRO line which has a heavier, simpler, but cheaper rail.

What does a short stroke have to do with getting dirty...?

I've taken my pws to a couple classes and saw several DI guns go down both times.  Mine after 1k rounds was so clean I could have skipped cleaning it.  All of it was suppressed too (556k flow).

by “short-stroke stoppages”, I mean failing to complete the reciprocation portion of the Cycle of Operations.

A gun being clean while using a flow through can doesn’t really demonstrate anything, except for how much piston guns prefer them.

I think everyone who wanted them already "got both" but of course there are always new buyers entering the market as they come of age. Overall, piston ARs have never commanded anything except a minority of the AR market share, but yes they were all the rage in online discussions many years ago.

The 2 main detractors from people buying piston ARs are cost and additional weight, in that order. Then you've got additional mechanical complexity and lack of interchangeability with all the "standardized" AR parts. Some may choose to avoid one for that reason.

The advantages of piston ARs are better realized when you're firing a significant amount of full auto, get them really hot, and don't want to be bothered with adding oil into the BCG. Most shooters never end up in that scenario. That's where they shine though.

Yeah they keep some carbon fouling out of the BCG, but mainly they keep a lot of heat (gas) out of the BCG and few people ever talk about that. Heat dries out your lubrication and causes parts like springs to fail sooner. Conventional DI ARs like to run with a lubricated BCG and it just dries them out if you fire them like crazy all day every day for a week straight, and don't stop to execute cleaning & lubrication. Once they're dry and fouled, they're much more likely to experience a failure, unlike the properly-executed piston configurations. That's exactly why JSOC bought the 416. They didn't want to have to stop to do that in the field.

A properly maintained conventional (DI) AR runs as well as anything else (better than most) when properly maintained, and that maintenance isn't difficult, laborious, or time-consuming so for most people there's no reason not to choose the more common system that also weighs less and costs less.

Fortunately we all get a choice, and there are lots of great choices out there. So get what you want.

The one I kept is a Caracal 816 A2 in both the 11.5" and 14.5" configurations.

Whoops. Already hit this thread.

Same thing here.

Nothing wrong with DI, I love mine, but my PWS is fire....

Umm. lol?


You can run that DI gun for a long time with no issues.

Field cleaning necessity is from other environmental materials getting into the gun, and that happens with internal piston  or external piston guns.

necrothread

so shooting suppressed with a piston gun isn't an advantage?

I have both.

The weight, extra parts and weird carrier / upper wear are the downside. The upside is a cooler and cleaner upper for heavy firing schedules, dirty ammo and suppressed shooting.

My experience was 20 years ago or so, I noticed that a lot of DI guns would only reliably run 3-400 rounds before fouling started to become an issue. That's what got me interested in piston guns.  

For whatever reason, I just don't see the fouling issue these days. Maybe the ammo is a bit cleaner, maybe there have been minor AR design or manufacturing tweaks that fixed it. IMO these days, there isn't much advantage over a good quality, properly tuned, modern DI gun. And I shoot way more suppressed now, than back in the day.

As someone who has burned thousands of rounds through both:

Not really.

Depends on your gas system length and if it is reduced for suppressed shooting only. I have ran both. For barrel lengths longer than 11.5" in a carbine gas system to mid length DI makes a lot of sense. once you run lower DB cans a piston simply runs longer between service intervals. I have a few AA systems with CHF barrels from DD and CA that work well with K-cans. I recently picked up a gen2 SIG 516 14.5 that is a very nice shooting rifle and due to the gas block settings allows me to run a standard weight carbine buffer and spring. I also have a nice Gen1 POF P415 with the Mike Rock fluted barrel which is more like the FAL system than the other over barrel style piston ARs. the AA uppers are a little snappy on the recoil but easy to get used to. The 516 is easily the softest recoil impulse of my piston upper followed by the POF P415. When suppressed they all are much less gassy than my DI 13.7 mid Noveske DI with BRT 0.078" gas tube. I never minded the weight of my rifles as I'm over 225# without kit and have done some competitions in full kit with them. I've shot plenty with good DI uppers like the DD Mk18 and the Geissele Super Duty rifles both suppressed and bare. Given the choice for CQB where cans are required I'll always take my AA 11.5 rigs. FYI the VLTOR A5 buffer system is amazing and given the time and extra money I'll eventually switch all of my rifles to it. At the end of the day run what you like and be proficient with it. Happy shooting gents!

What is advantageous about it? Generally speaking it does the same thing. From my research GPU's seem to exhibit a greater sound signature and unlock earlier. Neither of which is particularly advantageous.

Shooting suppressed a lot I can see the merit. But end of the day they just aren't all that much better.

One day I will have a JSOC 416 clone, but I still prefer DI for simplicity and parts availability.

Not quite.  6.8x51mm is only for infantry, everyone else still gets 5.56mm.  Guns still need cleaning.  There is no free lunch, gas pistons just deposit carbon up front.

If we are being honest the debate on reliability, supressed shooting and such is one that 99% of buyers didn't care about;

Most of the conversion systems (Adma Arms Style) sucked and added significant cost to make the weapons unattractive to the average joe.
Dedicated piston guns in the early days suffered the same issue, most were significantly more expensive than a DI gun.
Even now, a decent piston upper is around $800, when the average guy can buy a complete DI gun for $500 from PSA.

On economics alone piston guns will never have the popularity.

Attached File

Attached File

Doesn’t seem fair to compare to a non-AR piston model (upper). This piston alternative is the same price… https://gunzonedeals.com/product/adams-fgaa00426-p1-rifle-moe-5.56-16in
Probably has more to do with non-proprietary parts in my opinion.

This. I am trying to find parts for a Osprey kit right now. Only need the receiver bushing I believe.

If they’re hard to find, consider the AA bushing instead… https://adamsarms.net/product/upper-receiver-bushing/

Gas piston just deposit carbon and copper up front then in back. Here’s a Mk48 gas chamber in front of the piston. One cleaned and one neglected. Then there’s the deposit on the front of the op rod. M249/M240 same. Both reliable systems but both require cleaning.
Attached File

Attached File

Same.

Also, since heat came up, there is no practical advantage for a piston gun “running cooler”. No one here has ever melted a M4 bolt or carrier. You can dump mags (plural) through it suppressed on auto and immediately touch the bolt without burning yourself.

Hey mine goes bangand less clean up

It isn't just cost though.

All the guys buying mid grade, much less top brand ar's could easily afford a comparable piston gun. And there are some high quality piston guns. But most, for some reason don't bother with them.

It could be the weight. It could just be the advantage of having the most ubiquitous rifle, with greatest logistics support and so forth. That was what made Glock great IMHO.

We shall see if designs like the newer HK and Sig ever displace the conventional design. The military seems to be going that route now.