I've been reading & lurking here for some months as I'm thinking of an LMT upper or AA system which leads me to ask if the guys & gals who installed or purchased a piston AR--does it help with accuracy? Do you still use it, or did you unconvert it back to DI?

I have both, and jumped on the piston bus pretty early. Mine is a POF.  Works well, you still need to clean of course. The bolt stays pretty clean, piston area gets filthy.  Might be a slight edge in reliability..very slight.  I rarely have reliability issues with either platform, and they are usually ammo related.
 Piston systems could be a solution in search of a problem.  I still like shooting my piston gun, but I won't buy another.

Mine is on par accuracy wise with my DI guns.

It really depends on your needs.  I live in a tropical environment with high humidity, salinity and temps so if I don't clean it while its still warm the carbon swells and hardens harder than hard causing problems the next time around.   I always test my rifle for reliability and accuracy before adding a piston so I have a before and after comparison. To date there is little to no difference in accuracy.

As the other poster said, it also makes cleaning the rifle a breeze compared to cleaning a DI BCG and receiver.

Is it? That is only something you can answer. To me I believe it is. I like a cleaner running rifle and being in the Army I tend to not enjoy cleaning weapons as much as I used to.

I have two piston guns and prefer them to DI guns.  That is simply a personal choice.  DI rifles work just fine and it is a proven system.  I just like clean bolts.  Accuracy is the same in my opinion.  The advantage to a DI system is parts availability in a crisis plus the ability to cannibalize another rifle for parts.

Clean innards, relative to DI-- I run carbine courses with my PWS, and after an entire weekend (800 rounds maybe) it is cleaner than running 2 mags out of a DI.  A couple blasts of brake cleaner in the chamber mouth area, wipe off the bolt, and done

You can argue all you want about how easy it is to clean an AR, and reliable the DI is proven to be, but it is impressive how much CLEANER the piston system is.  Probably less gas blown into the shooters face also.

As a lefty that shoots righty uppers the piston was a Godsend.  When you have to run DI wet, with an ejection port near your ear, it spatters your eye protection with a fine mist of oil.

The other reason I went that way was to keep the systems seperate.  While the DI system is proven reliable, I know that heat cycles are what kill metals by multiplying the effects of fatigue.  By removing those heat cycles you can greatly extend the life of a metal (just ask your transmission).

I also would hate to think I had to change a firing pin at the worst time, as that's when it will break.  If you've been shooting extensively your BCG will be several hundred degrees and you will not be able to handle it to make that change.

Finally I don't have to carry lube with me.  I have grease in all my internals because it never burns off.  I occasionally relube the bolt lugs and the cam pin and the outside of the carrier, but when I've done it there was still plenty of lube there as it just doesn't burn off.

Ultimately both work, I just prefer pistons and the advantages they have for me as a shooter.

"Piston system: Is it worth it?"   Yes

Yes.  They are worth it.
Unrelated to accuracy.
Yes I still use them.
I also have nice DI guns which I still use.
The pistons are nice for hard use and require less lube, cleaning, and maintenance - particularly suppressed which applies to me.

i keep my guns clean.

mine's an AA, the melonite barrel, gas block, and piston makes it easier and quicker to clean.

IMHO not worth it.

I ran 4,500 rounds at DARC without throughly cleaning my 12.5" DI gun. (Oiled the bolt a few times but I didn't do a detailed cleaning,)

It ran like a scalded dog.

The piston guns are heavier and not as accurate.

A buddy of mine runs AA piston guns. He always seems to be in a pickle when he wants to swap rails etc. because of ID, blah blah blah.

DI guns offer more versatility.

Wow you guys run a hard bargain, so let me ask a question seeming as though I've never had a piston rifle.( other than ak's). If you were in a jungle for six months with no oil or cleaning gear and it rained 2" every day and you were expending hundreds of rounds in a combat situation what type would you actually want and need?

Gonna hafta call horseplop on your less accurate claim. My current shooters are barely heavier than DI rifles with similar set-up.

Anyhoo, what I run now has more to do with other features they have than piston vs. DI.

For me no.  

I have a early AA sitting in my parts bin. It made through 1 2 gun course and fell apart.  

C clip broke off and parts were lost during the course , I called AA several time with no response back.

The same rifles I own or KAC, or DD, or PWS, or LMT, or (with some lucky lotto #'s) HK. Many solid shooters out there, piston or DI.

In the many Service Rifle matches I have attended, I have seen quite a few Match Rifle category class AR based rifles. I have yet to see one of them be a piston.  

Piston is a potentially interesting choice for short barreled AR's intended for full-auto fire with a high round count.  Aside from that, I have yet to see the advantage.

Most if not all squad and heavy machine guns are piston guns, they are reliable and run well. Some of the best service and military rifles were piston guns from the M1, M14 , FAL,AK, etc.
DIrect gas works but pistons are believed to work better in harsh conditions.

I bought mine (LWRC M6A2 SPR) because I was able to get it for less than dealer cost.

The fact that I didn't already own a piston AR played a small role too.


After less than 1k rounds I can say a few things:
1) No more or less accurate than a DI rifle
2) Cleanup is ridiculously easy.
3) Recoil impulse is different than DI


I love the rifle, but I wouldn't feel undergunned with any of my other DI ARs.  

The rifle was certainly worth the money I paid.  Premium parts, well-machined (bolt carrier is impressive), innovative rail system.  I've spent more building a high-end DI rifle.

I currently only own piston rifles.  So, for me they are worth it.  I prefer piston for the ease of and less frequent cleaning.

I might buy a DI gun if I find the right deal, but I'd rather have another PWS.

Never ever going back.

I have found the same 3 things to be true.
Gas piston is an AA upper & lower middy.
DI is a 20 year old Bushmaster Dissipator A2 with very heavy barrel, which makes the AA lighter.
Both are collapsible stocks, but the AA has a Vltor Emod, the Dissy has the AA M4 stock.

Now that I've put a couple cases through it, the cleanup is ridiculously easy.  I always feel like I'm missing something when cleaning because there's no mess.

I'm impressed.  If I had the cash handy right now I'd get another LWRC.

Not worth it to me.  If I was an operator or LEO then probably yes.

This is a really informative thread for those like me that have no experience or knowledge of the piston ARs.  Thanks

Most of my rifles use pistons the ones that aren't probably will one day.

I only have DI experience at this time but am not biased either way...more of a 6-of-one-half-dozen-of-the-other kind of guy.  I see a lot of merit to both designs and more overall similarities than differences.  They are still AR designs, after all.  I only have AR-10 platforms currently.  Buddy of mine has an LWRC 5.56 that is mighty sweet.  I tend to think that recoil is hard to measure between the two systems in 5.56.  I have not fired a large caliber AR with a piston system.  I see some comments about different recoil with piston rifles.  My 7.62 DI rifle has almost no recoil.  It's one of the things I was most impressed with on that rifle.  Anyone with some substantive experience in large caliber piston system recoil vs. DI?  You hear some arguments about the piston/rod system taking some of the "inline" recoil benefit out of the mix compared to DI.  I can't see much impact in 5.56, but what do some of you think/experience with 7.62?

Edit:  My current search for a different handguard set for my AR-10 also got me to thinking about the gas piston design.  With the mechanical attachment of the piston rod with the BCG, does this make trying to isolate the barrel with a free float handguard not worth it?  On the other hand, I can see the piston rod having less effect on the barrel than having the barrel pressed from the bottom while it rests on a solid object while shooting the rifle...or does it?

Got into the piston game about 4 years ago, and I'm absolutely a convert.
The felt recoil is DIFFERENT, but I really don't see what people mean by it being INCREASED. It almost feels like mine has a slight springy feeling to it, but nothing really noticeable. If you're worried about increased felt recoil with a 5.56mm round, you should probably go back to shooting .22's.

Same goes for the "added weight" argument. The weight is really a drop in the bucket. Especially if you're running a gun with rails, and a heavy profile barrel.

Personally, I love the ease of maintenance. It takes me like maybe 10 minutes to clean my AR.
Presently I'm running a first-gen Smith & Wesson M&P-PS. I'm gonna redo my gas system and install an Adams Arms XLP gas block with carbine length rod so I can put a rail on it, and because S&W doesn't make that style gas block anymore, so I'd have to replace the system anyway with the new style gas block if something were to break.

Seriously...... Jungle ,six months , no oil,cleaning gear, rained 2 " everyday..... Carry an AK .. Your not so much worried about accuaratcy, your in a thick jungle. There is alot of what the AK is not.. But being what everything else is compaired to when you bring up reliability is the AK's claim to fame..... Im a AR fan, but what the AK strong point   is can not be argued. Or shouldn't be argued... IMO WarDawg