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Thread: differences in gas port sizes

  1. #1
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    differences in gas port sizes

    Need some help locating the thread that had the different brands gas port sizes listed. Running out of ideas to put in the search box to narrow the field down.


    Thanks

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    found the thread I was looking for.


    http://m4carbine.net/showthread.php?...highlight=port

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    Quote Originally Posted by mvician View Post
    found the thread I was looking for.


    http://m4carbine.net/showthread.php?...highlight=port
    After reading that thread, great info by the way, I'm a little confused.
    Are the gas ports drilled by the barrel maker or the weapons company, LMT, BCM etc.? I would think that that's the barrel makers responsibility. I was curious about the SDI barrel I'm using for my project and happy to see that it measures out to .063. Would a lower tier manufactorer contract barrels from a maker w/ larger or less consistent gas ports at a lower price?

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    Gas ports should be consistent for size. A sloppy manufacturer may push the drill too long, and have some oversize ports within a given lot of barrels.

    Gas port sizes are all over the map. Each manufacturer seems to have his own idea of the "correct" size. .063 is the smallest carbine size I've heard about. I believe LMT runs theirs .071? Correct me if I'm wrong.

    Rifles can run .093 to .099. Slightly overgassing will cut down on operation issues. I don't think this is a reflection of poor workmanship or quality.

    Mark15

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    Quote Originally Posted by Mark15 View Post
    Gas ports should be consistent for size. A sloppy manufacturer may push the drill too long, and have some oversize ports within a given lot of barrels.

    Gas port sizes are all over the map. Each manufacturer seems to have his own idea of the "correct" size. .063 is the smallest carbine size I've heard about. I believe LMT runs theirs .071? Correct me if I'm wrong.

    Rifles can run .093 to .099. Slightly overgassing will cut down on operation issues. I don't think this is a reflection of poor workmanship or quality.

    Mark15
    LMT runs .071" on 10.5" guns, their 16" guns are typically .063" unless you have a lot of rounds through them and have eroded open.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    I emailed Bravo co. to ask about their 11.5 in. barrels and I was told that they are .076.



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    Typically, your lower tier AR manufacturers are going to use gas ports in the .078-.085. Range. Why? because they do not want to get calls to their CS Dept. complaining about their bolts not locking back.

    What the consumer fails to realize is that the extra pressure and heat causes faster wear on the weapon and greater recoil felt by the shooter.

    The other thing to remember about gas ports is that they erode. So when you start out with a weapon with a large gas port to begin with, it is only going to get worse.

    C4
    Last edited by C4IGrant; 07-03-09 at 15:56.

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    seeing as though the OP found his answers, i'm hijacking this thread a bit.

    Grant, in your 11.5 in Bad-Assed upper thread, you implied that you're running a smaller than normal gas port size. could this fine tuning be done by an "adjustable" gas block? if so, any suggestions on a high quality one?
    "you give peace a chance, I'll stay here and cover you, in case it doesn't work out"

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    Quote Originally Posted by theJanitor View Post
    seeing as though the OP found his answers, i'm hijacking this thread a bit.

    Grant, in your 11.5 in Bad-Assed upper thread, you implied that you're running a smaller than normal gas port size. could this fine tuning be done by an "adjustable" gas block? if so, any suggestions on a high quality one?
    Yes, you could do that. PRI and JP both makes some and have messed with both. I find neither of them acceptable for serious use.

    If you want a gun to have multiple gas port sizes, get a Noveske SB.


    C4

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    i thought the SB was on/off?
    "you give peace a chance, I'll stay here and cover you, in case it doesn't work out"

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