Piston system vs Gas questions?

Discussion in 'AR-15 Discussion' started by Niescior, Feb 27, 2014.

  1. Niescior

    Niescior New Member

    I have heard and have done some reading on piston vs gas, and have suffieciently heard piston has the advantage because it doesnt spew carbon and debris all over the BCG, so I just have some questions on this

    If I have a gas system, and I would like to change it how would I do that?

    How much would it cost?

    and do I need a different BCG with a piston system?

    Thanks very much.
  2. FernandoTheCommando

    FernandoTheCommando New Member

    I'm sure the ar experts will weigh in soon , but I'm pretty sure the bcg for a piston system is proprietary. As for the advantages, keeping the chamber clean seems to be the main draw to a piston system. Some issues (that some higher end companies seemed to remedy) are carrier tilt. The carrier being struck by the piston will not move straight back and will wobble a bit and rub the buffer tube. Rugers sr556 now has an updates bcg that is rounded in the back to combat that. Lwrc has done a great job of controlling carrier tilt in their rifles. I'm not new to guns, but I'm new to ARs. I like the piston systems but I think some day ill buy a DI gun as well. Is there a particular brand you were thinking of buying? Just curious.

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  3. Gatoragn

    Gatoragn Active Member

    An Adams Arms conversion will run $400 or so. Not worth the cost. I had a Huldra (piston upper made by Adams Arms), but I sold it during the panic and got all of my money back plus the LGS earned his consignment fee.

    If you want a piston upper, sell your DI and buy a piston. But don't butcher your functional DI upper to create a piston upper.

    This is just my $0.02, it is your money.

    Yes, you need a BCG designed to run with piston.
  4. Niescior

    Niescior New Member


    I do not even know what brand to look toward yet, and honestly this is more for information sake and knowing how to do it and what goes into it.

    But thanks for the info.
  5. texaswoodworker

    texaswoodworker New Member

    The piston system ARs are 99.999% reliable, and keep the chamber a bit cleaner than a DI AR would, but they weight more than the DI ARs and cost a lot more than most DI ARs. DI ARs are 99.998% reliable.

    So is a very small amount of extra reliability, and a little less cleaning worth heavier rifle that costs a lot more?

    To give you an idea of the cost difference, I built a DI AR out of really good parts, and it ended up being around $1200. Some good ARs can be had for as low as $600-$800. The Ruger SR-556 has a MSRP of $1995. If you just want the upper, it's still $1499.
    Last edited: Feb 28, 2014
  6. Mercator

    Mercator Active Member

    Yes, you'll need a different BCG, basically a complete piston upper. Those cost as much as another good AR but are available.

    Your chamber will foul less, but you will have the dirty piston assembly to clean. Overall, pretty much zero sum. The only rational reason for choosing a piston driven AR is using a suppressor. A piston system like the SIG 516 can show extraordinary versatility in adverse conditions, the kind we as civilians are not subjected to.
  7. ams556

    ams556 New Member

    I know this is one of those divided arguments but I would stick with the gas system. Proven, reliable, interchangeable parts, and cheap.

    If your worried about a little extra time cleaning and have money to burn. I started reloading, after playing with my loads a bit I ended up with a load that is accurate and efficient( less unburnt powder) in another 500 rounds my reloading investment will have paid for itself. Which one it warms up, won't take long.
  8. JonM

    JonM Moderator

    If you want a piston gun don't do it to an ar15. Sell what ya got then go get a rifle designed to be a piston gun from the get go.

    Truth of the matter is pistons aren't cleaner or more reliable than di guns. They just accrue gunk in different areas. The amount of cleaning is the same.

    Installing a ad on piston system you almost certainly going to decrease reliability as the diy kits aren't the greatest. You will turn your rifle nose heavy and increase weight.

    The ar15's dirty little secret is its di system IS a piston design with the bolt acting as the piston portion. Stoner just put the piston on the tail of the bolt instead of waaaay out front. Doing that simplifues operation decreases weight and makes it vastly easier to repair in the field. You can even jury rig gas rings for the ar15 out of bits of common wire if you really had to.
  9. bluez

    bluez Well-Known Member

    Adams arms makes a conversion kit.

    I owned a Adams arms before and liked it.
    Not as pretty as the off the shelf systems but works.
    I've owned many DI's and many piston AR's

    Some real nice and high end piston guns out there and some more affordable ones ( Sig516, SR556 RRA piston ) are out there but they are all more expensive than DI guns.

    I am a bigger guy so I dont mind that Pistons are usually a few ounces heavier and i love not having to clean my rifle after every use.

    I usually let piston AR's go about 1000 rds between cleanings with no ill effects, thats about the time the barrel needs cleaning.

    But nothing wrong with DI guns either.. the parts are interchangeable since they are so common and Daniel Defence, LMT, BCM and Noveske make some fine DI's.

    Most my ARs now are Pistons mostly because i find them interesting and they have a certain purity to them as even the dirtiest ammo cna be shot with no ill effects since the gases get vented out right away.
    Last edited: Feb 27, 2014
  10. sweeper22

    sweeper22 New Member

    If I'm buying a piston rifle, it'll be something designed from the ground up in that direction....like an AK.

    There are a number of reasons why my ARs are not piston driven:

    • They cost more
    • Lack of interchangable parts
    • Heavier, and less balanced (often front heavy)

    None of this should imply that a piston AR can't be a really good rifle. But there are other upgrades that make more sense for my tastes. Your money, your rifle. My tastes should have little impact on your decision.
  11. Niescior

    Niescior New Member

    Thanks a lot for the info guys, it really helped.
  12. okdonk

    okdonk New Member

    Also check out PWS if you are still leaning to piston.
  13. jord1985

    jord1985 New Member


    My friend has a AR with huldra (made by Adams arms) piston upper. With mid length piston/gas system.

    It's actually lighter than my DDM4v5.

    The DD rail vs his magpul moe handguard adds a lot of weight. Other than that our stocks (STRs) buis (troys) and everything else is the same weight wise.

    The only difference is his bolt stays cool to touch after firing and the recoil on the piston seems a bit snappier even with the same length system.

    Just thought I'd dispel that myth that it's "ALOT" heavier. People think piston and the idea of that heavy wooden AK clunker gets lodged in their minds. The weight is negligible ...... I'll take big words for $300 Alex. Goodnight all.

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  14. sweeper22

    sweeper22 New Member

    This might be true. I have a DDM4v3, but that's as close as I come to experience with either of these rifles.

    What I can say, is that every piston AR I've handled/shot is expensive and poorly-balanced (front-heavy). Maybe I simply haven't experienced the right ones.

    But the lack of interchangeability would still deter me some.
  15. cjn79

    cjn79 New Member

    I will eventually get a piston driven rifle but I'm fine with the DIs. Going to give it a year or two and let the bugs get worked out and hope the price comes down. Maybe parts availability will be better as well. My personal favorite is the Barrett Rec7. From what I have read they are one of the leaders in this area.

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  16. Ishooter

    Ishooter New Member

    I have DI and piston systems. I have the Adams Arms pistom system and the only thing that is different or not interchangeable is the gas block. That isn't interchangeable with the DI system because it holds the gas valve that makes the system work. I guess you would say that the gas tube isn't interchangeable because you replace it with a rod. The bolt, barrel, stock,hand guard and all the other parts are interchangeable.You can use any bolt in a piston system. There are some systems that use a special bolt carrier. On some of the bolt carriers the place that the rod goes into is cast into the peace rather than bolted on. That may be a weak link. I don't know, I have never had any problems with mine.

    As far as price goes, I paid less than $600 for my Adams Arms upper. I got it on sale. Midsouth Shooters Supply has them for $601 and change at this time. I paid $550 and change for my DI upper. So the piston system does cost more.

    As far as being front heavy that would have to do with the barrel and hand guard that is on it. The one I have is heavier than the DI system my wife has but she has the thin barrel and I have the light target barrel. Mine is heavier. The only weight difference in parts between the two systems is the rod over the tube and the nob on the gas valve. That might be a OZ.

    Cleaning the two systems is like night and day. With the piston system the bolt is no dirtier than a turn bolt. On the DI system you know what has to be dun to clean the bolt and bolt carrier. Brush scrub and soak then repeat till clean. I like and use both systems. Cleaning the piston system is much easier. If it isn't cleaned it will work longer than the DI system not being cleaned. I clean all my guns after each use so that isn't a problem for me.

    If I was packing a gun In the field that I couldn't clean for one reason or the other. I would want the piston system. If you are not heating up the parts that move with the gas that make the system work then the parts have to last longer and stay cleaner.

    Just my thoughts about the ones I own. I don't know about all the other piston systems that are made. I only own the Adams Arms system and it works well. The DI system that I have and my wife has are great rifles and fun to shoot, but they are a pain to clean after a good range session. I hope that helped answer your questions.
    Last edited: Mar 2, 2014
  17. Quentin

    Quentin New Member

    Good advice above. It makes little sense to alter a properly functioning DI upper hoping an Adams piston kit will make it work better. A fool's errand if you think about it. If you're absolutely sure you need a piston AR (after articulating each reason YOU need it) then buy one from a manufacturer known to make good piston uppers/rifles. Most civilian applications do not benefit from a piston AR, however the manufacturer benefits from selling them. Think about that as you read all the ads in the gun rags. There's a reason why they spend so much on advertising! I'd take that money and buy something that you'll clearly benefit from using. Like good optics or ammo.