Putting Out Feelers On Piston AR's

AR/M4 AR General Discussion
1

Welp, it’s been just over 3 years since I first joined the site (see here: https://www.m4carbine.net/showthread.php?t=4026 ) after getting back into the AR scene with an M&P15 that has remained my only rifle since then.

Mention was made at the time of piston AR’s slowly gaining popularity, but with conversion kits still being widespread. I’ve have noticed that factory built models have gained a lot of presence in my local stores since then, but I still know very little about them.

So I’m just looking for any general considerations regarding the piston AR, possibly as a new item for me to usher in the Spring shooting season. A really cool option would be something with a folding stock, which of course our gas guns cannot accommodate.

A couple of questions that readily come to mind include:

(1) how does feel and handling compare to conventional gas AR’s, both in actual shooting but also overall weight, balance, etc.?

(2) how does reliability compare?

(3) what cleaning and other maintenance issues are there?

(4) what makes and models are particularly of note (especially any folders)?

Thanks for any input.:slight_smile:

2

I think piston ar’s handle the same as di ar’s. I have yet to hold or shoot one though. With that said, I don’t thing the weight difference is much. As far as reliability, well that’s one of the selling points I think. As long as you have good mags and ammo that isn’t questionable, you will have no issues. As far a makers, LWRC, POF, Adams Arms.
I don’t know if I would go with a conversion kit. I think a dedicated upper is the way to go. I hope this helps. Remember to post pics of your decision!!

3

Randy, for the stuff you use a carbine for, I honestly don’t see having a piston AR would do anything for you that the DI guns won’t.

If you shoot a lot of suppressed, if you shoot a lot of full auto, and if you shoot a barrel less than 14.5", then yes, a piston might offer some advantages.

Otherwise, they usher in a lot of new issues.

If you really want one, I’d look at the LMT MRP, or save your pennies up and get a HK when they finally come onto the market.

Or you could always pick up another Arsenal Inc. SLR-106FR…piston, folding stock… :cool:

4

Plan B. :wink:

5

Your quest for a folding stock is going to take you away from the AR platform and ito other systems like the AK, FN SCAR, SIG, Remington/Shrubmaster ACR.

Of those, obviously I’ve got the most experience with the AK and after that, the SCAR. Most of the ergonomic issues with the AK can be worked around with the addition of a Blackjack safety lever, or the later generation of Krebs safety levers, an Ultimak gas tube rail and an Aimpoint T-1 or H-1.

The SCAR is a great system, but it’s not cheap, although prices have stabilized a bit.

The ACR should probably be given some time to prove itself, and price stabilize. I’d also really like to see a 1/7" twist barrel as standard.

The SIG 556 seems to really be a crap shoot…which is unfortunate.

6

What is your reasoning for wanting a folding stock?

7

Every system has its own set of compromises, benefits, and system-specific issues.

The “no-cleaning” for Piston weapons is a massive myth. If you aren’t running a suppressor, you’re going to get much less carbon in the receiver/BCG/Bolt area; however, you’re trading that off for pure nastiness in the piston area. It’s easier to clean, but it still needs to be cleaned. It doesn’t do away with cleaning of the BCG/Bolt/Receiver, since you will still get funk in it, just not as much. So, at the end of the day, you’re still having to clean.

I’ve had the opportunity to shoot 2 different piston ARs, both owned by two different buddies, so my experience is limited to what I was able to witness with a small sampling. I currently own an unfired Ruger SR-556; unfired because I refuse to shoot it until I either get a PWS Enhanced Receiver extension: http://www.primaryweapons.com/STORE/PC/viewPrd.asp?idproduct=139&idcategory=, and/or Seth Harness’/Firearm Ready Solutions Anti-Carrier-Tilt Buffer: https://www.m4carbine.net/showthread.php?t=15453 .

Which leads me to your specific queries:

(1) how does feel and handling compare to conventional gas AR’s, both in actual shooting but also overall weight, balance, etc.?

Pretty similar. The shooting I did with my buddy’s SR-556 seemed pretty much like a normal AR, but with a slightly lower perceivable recoil impulse. I attribute this in part to weight, and possibly the short-stroke piston. There is a definite increase in weight in the piston-ARs that I’ve shot (SR-556 & POF 415). On my personal one, I’ve kept the flashlight and optic small and lightweight as to not exaggerate the weight (Single-Stage Surefire E2L & Trijicon RMR).

It seems lighter than my M&P15:

Obviously hardware/accessories choices play a part in this.

(2) how does reliability compare?

I don’t think there’s a gap, just different issues. The benefit to the DI systems is damned-near universal parts compatibility. This takes the logistics in regards to parts resupply out of the equation. With the piston systems, even if failure rates were demonstrably lower, which doesn’t seem to be the case, parts breakage is a bigger headache, since you’re typically dealing with proprietary, first-party hardware. Third-party support is essentially nonexistent for piston systems.

(3) what cleaning and other maintenance issues are there?

I don’t know why, but the manufacturers of PS seem to recommend not lubing as much as a DI AR. My personal stance is that they can, in the nicest way possible, go fly a kite. I did a lube-down of my SR-556 like I was going to go saltwater diving with it. Maybe I’m a stubborn mule, but metal on metal, creates friction, which creates heat, which creates problems. I’ll keep it wet.

The biggest issue that seems to present itself with the PS ARs is carrier-tilt. This is when the asymmetrical force of the op-rod is driving the carrier downward and dragging in the receiver extension.

Allegedly, it will eventually stop after a certain point, but this is why I’ve been shooting my DI ARs until I decide on a system to mitigate the tilt. Right now I’m leaning towards Seth’s ACT buffer. The ACT buffer has a nipple on it which is custom-fitted to your BCG. The BCG rests in this nipple, preventing it from tilting as it is thrust back into your tube.

https://www.m4carbine.net/showpost.php?p=357465&postcount=161

https://www.m4carbine.net/showpost.php?p=174294&postcount=1

(4) what makes and models are particularly of note (especially any folders)?

If I were going to buy a piston system right now, my main criterion for purchase would primarily be that the system was designed from the ground-up and not a retrofit. That’s just me. PSs are shoe-horned enough already into direct-impingement design, so, my mystical snake-oil beliefs are that any issues with a PS are going to be compounded by further forcing it into an AR by retro-fitting. That’s an unfounded/unresearched opinion, but I’m barfing it out there anyway.

If I had no AR, and wanted one, a piston-system would not be my first choice. Since you already own a DI weapon, you may want to delve into the piston realm. I’d recommend the SR-556, but frankly, I’ve only shot around 700 rounds out of my buddy’s, and I don’t consider relaxed, range shooting hard-use, nor a suitable test. FWIW, there were no issues encountered whatsoever, but the ammo was cheap, 55-grain Remington green-box ball.

I bought the Ruger because I honestly believed HK would never release the MR556. Though not experienced in my limited handling of the POF 415, I keep hearing errornet rumours about them not being able to make it through a class without some sort of issue. That’s why I went with the SR-556, since I did have a lot of positive experience in shooting with someone else’s. Again, I don’t know of anyone that’s done a class with one, so…

Robb (GotM4) didn’t have anything positive to say about the SR-556, nor did Grant (C4I Grant), and they are two individuals whose opinion I take seriously.

Frankly, 700 rounds isn’t enough for me to make a definitive conclusion on, but the only issue that I saw was wicked carrier-tilt; hence my reservations about shooting mine until I muster the scratch to score a fix. I’ve got myself spread pretty thin financially between my “Man-Cave” project and working on my backyard Zen garden, and the M&P15 is my main go-to smokewagon, so I’m not in a rush to get the Ruger “in the game”.

Just my limited experience, and opinion. Hope it helps.

8

This is the conclusion I came to a few weeks ago when I sat down to seriously evaluate whether I wanted to move to a piston AR. In the end, for what I do, the piston offers no substantial benefits to offset the issues they come with. So instead I’ll focus on revamping my DI guns and maybe getting something a little wacky like an HK93 clone.

9

I wrote this in another thread in reference piston guns:

As a frame of reference I have been hosting 2 to 5 tactical training classes a year, every year since 2001. A side from the classes I host I also take other training classes. I’ve been a full time Police Officer for 14 years, I’ve been a SWAT cop for 11 years, and I’m a Firearms Instructor for my agency, our Police Academy, SWAT Team, and SWAT Academy. Prior to that I was in the Marine Corps (Infantry / Security Forces).

In the early 60’s when the M16 first came on line there were several important people that wanted to see the M16 fail. So troops were told that they didn’t have to clean their guns, they used the wrong powder in the ammo (ie. they were suppose to use stick powder and they used ball powder), etc. By doing this the M16 got a reputation as being an unreliable platform.

In my opinion the reason that the direct impingement gas system (DI) has gotten such a bad reputation in recent years is because people go out an buy low end AR’s or they try to build a AR from parts from various manufacturers. They end up with a gun that is unreliable and this feeds into the myth that the DI gas system is unreliable.

When I was in the USMC the main malfunctions were caused from shooting blanks and magazine related. I had seen a hand full of other problems, but they were far and few between.

In the training classes that I host and take on my own and from the AR15’s that I see in training and qualification courses at work. Colt, LMT, BCM, Noveske, etc. run well. While CMMG, DPMS, Olympic Arms, Bushmaster, Stag Arms, RRA and others have a high number of reliablity problems.

Piston guns. I have seen a lot of piston guns that have had problems. I have never seen a POF make it through an entire class without problems. About half the Sigs that I have seen have had problems. About 1/3 of the LWRC guns I have seen have had problems.

From my experience piston guns

-have a sharper recoil impulse
-they are heavier
-piston system guns are more expensive
-the different piston systems are new and haven’t had the time to be as thouroughly tested as the DI gas system
-many of the piston system operate on a slightly different system

Piston systems on the AR15 is a fairly new concept (most within the last decade). The DI gas system in use on the AR15 has been in service for close to 60 years, this has given engineers time to work the bugs out of the DI system. Not the same can be said for the piston systems used on the AR platform.

In my opinion the piston system is not needed on the AR15 and it exists because guys buy lower end AR15’s, many of these lower end AR15’s are not reliable, and when a shoorter buys or builds an unreliable AR15 it feeds into the myth that the DI gas system is unreliable. DI gas system AR15’s are not created equal. There are different levels of quality.

A well known trainer has a DI gas system BCM upper that had 26,000 rounds through it before it was ever cleaned. Currently the gun has just shy of 29,000 rounds on it. Read this article for more info:


03designgroup | [b]BCM Complete AR15 Upper and Lower Receivers [/b]

In short I see no need to buy a piston upper. Buy a QUALITY AR15 with quality ammo, quality magazine, lube it, and it will run without any issues.

Hope this helps

10

AR was not designed to begin with to work with a piston system, and these are piggy back add ons to a platform not designed for it. This is why there seems to be quite a few issues with them, and why you see the companies making them constantly coming out with new versions of different parts. You are basically buying a gun, and beta testing it for them so they can get feedback to make improvements.

For instance an LWRC purchased a few years ago is quite different from one purchased today.

My experience mirror UCMC03’s in that I have found the DI system to be very reliable (when starting out with a quality gun). I spent 6 years in the Army, and have operated the M16 family in almost every single environment out there. -20 in Germany, 120+ in Kuwait and Iraq, South Carolina in BCT, forrests in Washington, etc.

The most numerous issues I saw were a lack of maintenance and lube. People would go out to qualify, and their gun would be bone dry. A squirt of CLP, and they failed to have any more problems.

2nd comes bad mags. The supply rooms are filled with old worn out magazines. They were designed to be disposable items, and should be treated as such. On the civi side there are a lot of junk mags out there. Ive seen such used mags there was barely any hint of finish left on them. That is years of use. The PMAG has finally come around as a reliable magazine, and an improvement over the USGI w/ green follower.

Shooting with a can is debatable. The AR was also not designed to work with a can for 1k plus rounds. Even in military usage you would be hard pressed to find of any instances of someone shooting with a can for that many rounds in combat.

11

Short barrel, full auto, and suppressed… otherwise its not needed.

12

Since when is it about “need”?

“Need” is the “N-word” and is a four letter word, too. Pay the webmaster $2 and carry on, sir. :stuck_out_tongue:

13

I have owned 3 LWRC models and they have functioned flawlessy. For me the 2 largest advantage points are the elimination of carbon build up which causes fouling and the heat disbursement is primarily handled at 95% in the front of the rifle.

Advanteges:

  1. LEFT HANDED SHOOTERS: No gas in the face
  2. SUPRESSED: significant gas reduction in the face
  3. HEAT: Parts last longer due to differentiated heat disbursement at the front end versus in the chamber.
  4. MUZZLE RISE: On the LWRC it is reduced due to the gas being released from the top forcing the muzzle to stay down when firing full auto or double taps.
  5. With the reduction of carbon build up and the significant heat reduction the extracters do not heat up and break as easily.

Just my two cents… Thanks for the post.

14

As a piston rifle owner, I’d agree with most of the folks on here - it doesn’t really “DO” anything a DI rifle CAN’T do, and has a number of eccentricities you’ll want to keep track of, that you DON’T run into in a DI gun, buffer tube erosion being most prominent among them.

I have a POF which I’ve made a number of improvements to, and still have a few to go. That said, to address your points;

(1) how does feel and handling compare to conventional gas AR’s, both in actual shooting but also overall weight, balance, etc.?

It’s heavier overall, and particularly nose-heavy. Muzzle flip becomes almost a non-issue, but extra weight can be a drag.

(2) how does reliability compare?

Honestly, I haven’t fired enough rounds to tell you. My Timney trigger seized up within 200 rounds though. Timney, to their credit, sent me a replacement at NO COST, no questions asked! Nonetheless, I replaced it with a RRA 2-stage, which has worked quite well - even in single-digit cold!

(3) what cleaning and other maintenance issues are there?

Cleanup is a BREEZE. Still got all the nooks and crannies to clean, like any other AR, but with all the elctroless nickel in the POF, that’s much easier too!

(4) what makes and models are particularly of note (especially any folders)?

Mine is a 415 Recon - 16" bbl, 12" rails.

I mentioned upgrades. To wit;

  • RRA 2-stage trigger
  • BCM extractor upgrade (black insert, NO donut)
  • H2 buffer & Dave Tubb’s flat-wire buffer spring
  • Ergo grip
  • Troy BUIS front & rear
  • Vltor EMod stock

These are just things changed from what came from the factory. I still want to add a PWS anti-tilt buffer TUBE soon.

I DO like my POF, how it shoots, the recoil, and the solid feel of it against my shoulder when deployed. It’s a rifle I know I can go to, and will get the job done. Piston rifles are NOT the proverbial ‘Star Trek phaser on setting 16,’ but if you have the money and time to spend, to set it up, they are a different experience.

15

Thanks for the many well-reasoned responses. This appears to be a topic of some interest, and I appreciate the time folks have put into sharing their thoughts.

I never intended a piston AR as a replacement for my DI M&P15, just as a possible new something-to-try-out. Based on the above responses though, I think this is a project I’ll shelve for the time being and maybe try something else for my Spring Fling.

Thanks again folks.:wink:

16

my experience with them is limited with one ar15/m4 based piston gun a lwrc m6a2 and from my point of view it kicks much harder no matter what we did to it we could not get the follow up shot speed we are getting out of my noveske afghan( we compaired these two because price is so close)
i do not know if this is a odd ball gun with problems and he has had to send it back twice with problems and from the reports i have read the guys running them full auto are having the same problems with the being unable to control the rifles

the guys at noveske have done some testing on the di vs piston setup and if you run a supressor like i do then you still get all the hot gasses in the breach of the weapon no matter what system you run because the suppressor holds gas and then it is directed back into the reciever on piston guns ( well documented )

i do own a piston gun but it is not a ar platform i have a scar-l and i love it and it has the folding stock you want but it is way way overpriced for what it is a great rifle set up correctly but it is its own type of firearm but it is one of my favorite the trigger is just horrible on it so i had to get it fixed for my with the price that are being charged for scar’s they should come with the best of everything and the trigger was worse that a bargin bin rifle imho

if you just take proper care of you di gun and do the proper cleanign it will always run i never had a di gun go down on me due to the gas system in my deployments in iraq or afghan and they are serving the military today i had other problems surface but never a di system issue

17

I, too, noticed the “sharper” recoil of the gas piston carbines starting with shooting a friend’s HK SL8 several years ago; not “a lot of recoil”, mind you, but noticeably DIFFERENT. More focus and technique is required for rapid follow ups. That said, I like the concept. Perhaps HK, LWRCi and LMT’s execution isn’t “perfect” but the engineering principles of the gas piston is, in my estimation, the most proper solution.

I think they all will run well for you and I who are not in active combat. Keep 'em clean and lubed (even if it is an LMT, LWRC or HK or Colt, Noveske, S&W…) after having taken them through a “shake down” run or three to your satisfaction and all should be good.

18

I have over 10k rounds through my 10.5" LWRC M6A1 (carbine length system) and around 5k through my 12.7" LWRC M6A3 (mid length system). The greatest advantage, IMHO, is that I don’t have to clean it as often and even when I do; I don’t have to scrape any of that black stuff off the bolt or from inside of the BCG.

The recoil is noticeably sharper (higher impulse) but is straight back so you should not notice any muzzle rise. I like my LWRC rifles. YMMV.

19

Para USA has their piston with a folding collapsable stock, 1/9 twist, it uses a different style piston system in that the bolt carrier attached to the op-rod it does not use a buffer. I have only seen it in a magazine article so I dont know a whole lot about it other than it exists and pictures of the internals