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Thread: rifle length gas, 16" barrel

  1. #31
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    Ran them as-wuz. .093. I later opened a few problematic ones up to .110 and it helped, but.... it still ain't the same o'course. It's like, if .093 is good with what, 6" of post-port barrel, and .110 is OK with 2", then would a .224 gas port with 1/2" of post-port barrel work? The slow, steady feed is better and more forgiving than the one big push.

  2. #32
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    Quote Originally Posted by Ned Christiansen View Post
    Would not have guessed that much but..... I could only guess. Doesn't sound unreasonable.
    2500 psi peak

    overall area under the curve ~4.2 PSIxSEC

    This is equivalent to 1400 PSI applied for 3ms.
    Last edited by Clint; 09-20-13 at 15:49.
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  3. #33
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    I, like Ned, have trimmed down a bunch of M16A1 barrels to 16.5" and had no problems. But, they were all used with, or planned to be used with, XM193, and not lower-powered ammo.

    My inside sources told me the peak pressure of the carrier was more in the range of 1200 to 1400 PSI, but I will check.

    Regardless of what the peak is, it does not happen immediately, and it is not the same as the pressure in the bore at the port. The time lag and duration matters.

  4. #34
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    Quote Originally Posted by Clint View Post
    2500 psi peak

    overall area under the curve ~4.2 PSIxSEC

    This is equivalent to 1400 PSI applied for 3ms.
    I have some pictures of a crazy bolt carrier that was made to take pressure readings at the BCG - that was a long time ago, but I think Diemaco did all the work on it. As I recall, they came up with 1500 psi "operating" pressure at the BCG for the M16.
    Please let me know if I have offended you...
    I would like to move on to my next task.


    I provide legal consultation and training - specializing in the Law of Gravity.

  5. #35
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    Well you can get a BCG to actuate pretty smartly with shop air so it seems reasonable that at 10-20X that it would throw the carrier back hard enough to compress the buffer spring and cock the hammer.

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