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Thread: Pistons and violent early extraction...

  1. #11
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    I doubt you could use any spring in a piston AR bolt carrier that would provide as much thrust on the bolt without pushing the carrier out of battery as a DI AR does with gas pressure. We are basically talking thousands of PSI vs a spring that could only supply at most 12 pounds of force before it starts to overcome the action spring.

    As to whether the gas pressure behind the bolt actually pushes it off of the barrel extension lugs, I really couldn't say, but I'm sure it at least cuts down the load on the lugs during unlocking.
    Last edited by An Undocumented Worker; 03-13-12 at 01:16.

  2. #12
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    Quote Originally Posted by An Undocumented Worker View Post
    I doubt you could use any spring in a piston AR bolt carrier that would provide as much thrust on the bolt without pushing the carrier out of battery as a DI AR does with gas pressure. We are basically talking thousands of PSI vs a spring that could only supply at most 12 pounds of force before it starts to overcome the action spring.
    True.

    Anyways, after seeing and inspecting a "few" 416's, I can say that the issue the OP has is really a non-issue, with that system at least.

  3. #13
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    Quote Originally Posted by Robb Jensen View Post
    If you want a piston rifle buy one that was meant to be one (AK, FAL, M1a, SCAR).
    Huge +1 to this. I love the people who take an AR and then make it piston driven and get .300 AAC... isn't that just the AKM? 125 gr bullet, 2300 fps, piston gun....

    Keep your ARs ARs - Direct impingement and 5.56. That's my opinion, anyway... not that I know anything

  4. #14
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    While the gases do push against the bolt, they cannot push the bolt forward! Although the bullet has exited the barrel by the time the expansion chamber fills with enough pressure to start the carrier moving, the pressure in the bore is still greater. Also, the spent case has expanded enough to take up what little slack there was and resist any forward motion of the bolt.

    It's also a fallacy to believe the AR does not have a piston. It's piston is part of the bolt and the carrier is a cylinder. The piston is inline with the bolt and bore, reducing muzzle climb induced by off center recoil forces and reciprocating mass.

    The AR does not feature primary extraction, a mechanical camming action that starts extraction as the bolt begins unlocking. Many other designs do, such as the M14 and most bolt actions. Whether the AR uses the original inline piston or an aftermarket offset piston relocated to the gas block, it must rely on "brute force" to yank the spent cartridge from the chamber
    Last edited by MistWolf; 03-13-12 at 06:46.
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  5. #15
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    I have one of each. I like my DI. I wanted a piston gun(just because). I like AR's not ak, fal etc. etc. blah blah. So....I built a piston AR! and I shoot the shit out of em both and don't worry about how many milliseconds longer the damn piston bolt lugs are taking to unlock from the exstension lugs than the DI bolt is or how forceful one process is over the other!
    Last edited by jet80tv; 03-13-12 at 03:16.

  6. #16
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    Quote Originally Posted by jet80tv View Post
    I have one of each. I like my DI. I wanted a piston gun(just because). I like AR's not ak, fal etc. etc. blah blah. So....I built a piston AR! and I shoot the shit out of em both and don't worry about how many milliseconds longer the damn piston bolt lugs are taking to unlock from the exstension lugs than the DI bolt is or how forceful one process is over the other!
    Shooting the gun takes a room temperature I.Q., understanding it is something you have to do on your own. You're starting to veer out of your lane.
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  7. #17
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    Quote Originally Posted by jet80tv View Post
    I have one of each. I like my DI. I wanted a piston gun(just because). I like AR's not ak, fal etc. etc. blah blah. So....I built a piston AR! and I shoot the shit out of em both and don't worry about how many milliseconds longer the damn piston bolt lugs are taking to unlock from the exstension lugs than the DI bolt is or how forceful one process is over the other!
    You should care, because those milliseconds equal material stresses that the weapon was not originally designed for.

  8. #18
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    Quote Originally Posted by Robb Jensen View Post
    Shooting the gun takes a room temperature I.Q., understanding it is something you have to do on your own. You're starting to veer out of your lane.
    that is a good one.

  9. #19
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    Quote Originally Posted by justin_247 View Post
    You should care, because those milliseconds equal material stresses that the weapon was not originally designed for.
    And how exactly did you come to that conclusion after reading MistWolf's post?

    How is the unlocking process of the bolt in the M16 FOW different than in an op-rod design, considering that the bolt cannot move forward?

    Also, I just spoke to the main armorer here, and he reiterated that there is no difference in the unlocking process between the two systems; the gas pushes on the carrier and the op-rod pushes on the carrier. The cam pin follows the cam track as the carrier moves to the rear, and this causes the cam pin and bolt to rotate until the lugs on the bolt are no longer in line with the locking lugs in the barrel extension.

    There will be wear on the locking lugs on both systems.

  10. #20
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    Why was this thread started again? Smells alot like the same old DI vs. piston crap again.



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