View Poll Results: DI or AA Piston for All Around AR

Voters
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  • DI! Save $ and weight. Get a carbon scraper, buy quality parts and reliability will be top notch.

    131 92.25%
  • AA Piston! Softer recoil, less cleaning. Can turn the gas down for a suppressor.

    11 7.75%
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Thread: All Around AR

  1. #11
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    Quote Originally Posted by No Bananas View Post
    The 10.5" upper w/ AA Piston Kit kicks softer than it did before when I bought it as a DI LMT upper. Maybe it's the additional weight of the AA gas block, I dunno. But it definately kicks less. Other folks who have an AA kit have the same experience. Have you ever shot an AA kit? I've never had a short stroke with the AA Kit, and I've never had a short stroke with the DI rifle I have either.

    PS: No malfunctions from the 10.5" LMT DI before I converted it.
    Pistons short-stroke more because the force from the gas must overcome the weight of not only the bolt-carrier, but also the piston rod. It's simple physics: more force is required because a quantifiable amount is lost to overcoming the inertia of the piston rod. With a DI gun, the only mass that needs to be moved is the bolt carrier. This means a round that is just barely powerful enough to run in a DI system has a very high chance of short-stroking in a piston gun. It also results in higher failure to lock back after the last round is fired.

    The act of piston rod hitting the carrier will jolt the gun, literally. Maybe you don't notice it, but it's happening nonetheless. It's the same reason that carrier-tilt happens. Instead of a smoother, more gradual gas expansion inside the gas key on a DI gun, the piston simply slams back on the carrier and the energy is directly transferred as a physical force into the upper receiver and into the rifle. The DI guns don't have this because their isn't a direct physical transfer of energy (since gas is essentially a fluid and will flow to the path of least resistance) and the only felt recoil is a result of the carrier connecting with the buffer.

    It's like a rope: you can pull on it gradually, or you can yank on it at full force. The piston guns will always have a "yanking" effect to them. DI guns won't (speaking relatively about the same gun firing the same round).
    Last edited by Skyyr; 03-02-10 at 18:36.

  2. #12
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    Dec 2007
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    You hate pistons, I get it. I hear what your saying about how it functions. Go fire an AA Kit. You'll see that the recoil is softer. In comporable guns with the same loads. I'm not saying that it is better than DI. Geez.
    Have Fun, Be Safe

  3. #13
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    Quote Originally Posted by No Bananas View Post
    You hate pistons, I get it. I hear what your saying about how it functions. Go fire an AA Kit. You'll see that the recoil is softer. In comporable guns with the same loads. I'm not saying that it is better than DI. Geez.
    I don't hate pistons; they just simply aren't superior to a DI weapon. They present a different set of problems that need to be overcome. That being said, you seem to be ignoring that physics will always be true. It is physically impossible for a piston to run smoother (read: without the jolt) than a DI system on the exact same gun. Maybe you don't notice it, but that's just it: you don't notice it. That doesn't refute the truth.

    Putting a piston on an AR makes as much sense as making a direct impingement AK. Can it be done? Sure, but there's no point to doing so.
    Last edited by Skyyr; 03-02-10 at 20:42.

  4. #14
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    Dec 2007
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    Jimini Christmas! Yes, I did acknowledge what you explained. I said I didn't know why the recoil seemed softer, that it could be the added weight of the heavy gas block:
    Quote Originally Posted by No Bananas View Post
    Maybe it's the additional weight of the AA gas block, I dunno. But it definately kicks less.
    Go to AA's website and see all the testimonials of folks who say it kicks less. go to some piston forums and you will see the same. Like I stated before, I understand what you are saying about physics and operation. But, it kicks less. Maybe it has absolutely nothing to do with their piston, maybe it's the heavy gas block, the weight of their one piece carrier or other physics that you don't know about. But those of us who have shot them and own them agree they kick less. In my experience and opinion an AA Kit kicks less than a DI. You have well established that you disagree. Now, hopefully we can let this go. Geez.
    Last edited by No Bananas; 03-03-10 at 21:41.
    Have Fun, Be Safe

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