Gas

Discussion in 'AR-15 Discussion' started by AznZOhAn, Jul 21, 2011.

  1. AznZOhAn

    AznZOhAn New Member

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    Is traditional blow back better or is piston better?
     
  2. Gatoragn

    Gatoragn Active Member

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    Bear in mind I am relatively new to AR's!

    Traditionalists will say the direct impingement AR's are the best.

    I picked up a piston upper about a month ago and I really, really, like it. It is an Adams Arms mid-length w/ 1:7 twist. I am of the opinion the future of the AR is going to be more pistons due to the need for less and easier maintenance. Google Huldra Arms and check out my upper.

    No matter what you buy, quality is the key.

    I have no reason so far to doubt either of my 5.56 (traditional & piston) uppers.

    A true blowback gun does not have a gas tube or piston to direct the pressure of the gases to the bolt. The gases created by combustion of the gunpowder literally blows the empty cartridge and thus the bolt backwards which is the beginning of the cycling process.
     

  3. luan87us

    luan87us New Member

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    Piston doesn't mean less cleaning really. All the carbon is by gas block and the hand guard where DI concentrate on the BCG. I don't see much different in the ammount of effort used to cleaning either one. If you want your gun to shoot and keep shooting you'll have to clean it either way. Remember that piston was not designed for AR platform. There is a reason why the military uses DI still today.
     
  4. mjkeat

    mjkeat New Member

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    I follow a similar train of thought as you do, luan87us. I have a piston and a couple DIs. My 1st was a piston and its been all DIs after that.

    That Huldra pistons are the future and DIs are dead sh*t caught a crap storm of resistance on the other forum and for good reason. Its a bs statement w/ nothing to back it up. Pistons are nice but they are far from the future of ARs. Cleaning isn't any easier. Like luan said the filth just collects other places.

    Like many have already said the piston AR is an attempted fix for a problem that doesn't exist.
     
  5. JonM

    JonM Moderator

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    Di is a more simple design than the piston. Less to go wrong. Had a piston gun didnt care for it. It wasnt any easier to clean since the gas piston collected the crud.

    I used an m60 for 5 years in the army loved it. But the damn piston had to be cleaned far more than the m16 to keep it running. If somone complains of a m60 not running well its cuz they didnt keep the piston clean. Pita. Same applies to any other piston gun. I find pistons harder to keep running for lots of rounds than the di system.

    If you get a piston gun make sure you can get to the piston area easily for cleaning. The reason ak run well is the piston pops right out and can be wiped off just as easily as the ar15 bolt carrier.

    Personally i would stay away from pisto ar they are a fad in my opinion
     
  6. fsted2a

    fsted2a Active Member

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    I have a piston and 2 DI guns. My piston gun has an ARES piston system, and I don't have any problems with it. I used it a lot when I was bumpfiring, but ammo is too high priced and hard to get now. Never had any malfunctions while running the ARES setup, even with the cheapest ammo. Just ran a boresnake through the barrel, wiped off the piston, and got ready to shoot again. 3 minutes tops to clean. I started running some teflon lube through my DI guns, and noticed very little carbon build up, and they aren't the dust magnets they use to be, so now I have mixed feelings. I read somewhere that the gas system on the original M16's had baked in teflon coating over electroless nickel, and a few companies are starting to put a nickel/teflon plating on the gas system parts, and calling it NP3, like it is something new. The M16A2 LSW did that in the 80's, and worked fine, but lost out on the contract to the M249 from FN. Quentin and I had a debate over DI vs piston a few months ago, and both have their pluses and minuses. I guess it depends on the builder and the shooter as to which you prefer. I intend to get a POF upper one day, as they are suppose to be the cadillac of piston AR's, and never need lube and very little cleaning. I will have to judge that for myself.
     
  7. JonM

    JonM Moderator

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    im not saying it wont run. all im saying is there is no difference in ease of cleaning. its just what end of the gun you like playing with better. just cuz its got an old style piston action doesnt make it any easier to clean. pistons in rifles been around for ever.
     
  8. Quentin

    Quentin New Member

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    Good answers above but your question is too vague. Care to narrow it down some? SBR or standard barrel, that type of thing... You tell us what your application is and then it's easier to answer.
     
  9. AznZOhAn

    AznZOhAn New Member

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    I would be cautious about the POF, I've Serb one malfunction and I've heard of another doing it also. The two that I speak of were breaking buffers and jamming.
     
  10. mjkeat

    mjkeat New Member

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    Good point Quentin. There are places where a piston rifle will start to shine, SBR'd and silenced being the brightest area.
     
  11. AznZOhAn

    AznZOhAn New Member

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    I have 2 DIs and had another, and I've never had a problem. In my thought process the DI would be better because: you're keeping all the heat on the front portion of the weapon, to access a piston under a free float quad rail would be a bother, cleaning a piston and bolt carrier wouldn't save time it would add more to it, DI has been combat tested and still in use today, DI has less moving part and that less to go wrong, and I would think a moving part over the barrel would loosen a shot group. I spoke with a former army ranger sniper(now a gunsmith), and he told me DI is better. He explained piston movement caused a barrel to flex which opened his shot group at 600-800 meters. The army ran a test between a DI AR10, piston AR10, and m14, the results were the DI had a tighter group and had less malfunctions. The only reason I asked which is better cause so many manufacturers have pistons now and hk says they're flawless(I don't see it).
     
  12. AznZOhAn

    AznZOhAn New Member

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    I'm going to build a 6.5 Grendel AR-15, with a 20" or 24" barrel, billet upper and lower, and free float battle rail. I am leaning towards the DI, but I want the better of the 2.
     
  13. luan87us

    luan87us New Member

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    Just keep in mind that Piston was not designed for AR platform. Imagine how much force does that rod take when it slam the BCG. IMO stick to DI if you want an AR.
     
  14. mjkeat

    mjkeat New Member

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    The piston system does not freefloat. You have a point of contact at the barrel and upper reciever.
     
  15. Gatoragn

    Gatoragn Active Member

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    I have no idea which is best, I like variety, so I am enjoying both.

    The piston on my upper obviously must pass through one of the holes in the barrel nut. I suppose if the hole is out of alignment, then there would be a point of contact. I cannot see where there is any more contact between the piston and the upper and the gas tube on my DI upper.

    Samson is one brand of free float rail systems for the Adams piston upper, but I don't plan to shell out $300 for one.

    The following is a quote from Adams website:

    The Daniel Defense 9.5 FSP Free Float Rail System features a cut in the front of the top rail to accommodate the front sight post and gas block of a carbine length AR15 gas system, while at the same time, providing much needed additional rail space along the sides and bottom rails.

    From everything I can see an Adams piston barrel can float as freely as the DPMS upper I installed a Hogue free float tube on. But I may be missing something.
     
  16. mjkeat

    mjkeat New Member

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    The piston system has to come in contact w/ the bolt in order to push it rearward. It also comes in contact at the reciever at the nut and the hole it slides in and out of.
     
  17. Gatoragn

    Gatoragn Active Member

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    My 50 year old eyes will be more of an issue than that amount of contact between the barrel and the upper. :p
     
  18. canebrake

    canebrake New Member

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    DI, its the oldest, like me! [​IMG]
     
  19. mjkeat

    mjkeat New Member

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    :)..............
     
  20. Quentin

    Quentin New Member

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    Well, as in about 90+% of all AR applications, there's no advantage to piston here. Stick with DI and buy ammo/mags with what you saved. :)