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Thread: Measuring the barrel gas port size

  1. #111
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    Quote Originally Posted by AR15barrels View Post
    Even though it has no bearing, it's still good to know who is more consistent, and who have crappy QC...
    and that's just it. This thread was started months ago in reaction to a bunch of people posting "what's my gas port size" threads. In the absence of any knowledge as to what it should be, or anything else to compare it to, and with no idea what they were going to do with that information once they had it, there wasn't anything for them to do with it. They may as well know what kind of batteries the smoke detectors take on the International Space Station.

  2. #112
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    Quote Originally Posted by rob_s View Post
    and that's just it. This thread was started months ago in reaction to a bunch of people posting "what's my gas port size" threads. In the absence of any knowledge as to what it should be, or anything else to compare it to, and with no idea what they were going to do with that information once they had it, there wasn't anything for them to do with it. They may as well know what kind of batteries the smoke detectors take on the International Space Station.
    I always get requests for gas port info.
    People don't realize the effort that I have into developing gas port sizes for all manner of different combinations of bore sizes, chamberings, barrel lengths, gas system lengths etc...
    I have a pretty wicked excel sheet going.
    I'm not gonna just freely give that work away to anyone just for asking though.
    If they have a problem and ask nicely, I will generally point them in the right direction, or offer to fix the problem, but 9 times out of 10, it's not even the gas port size...
    Last edited by AR15barrels; 08-03-12 at 18:43.
    Randall Rausch
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    California Precision Rifle Club founding member

  3. #113
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    Quote Originally Posted by SPQR476 View Post
    I have a hard time believing that this will work out to any degree of satisfaction, but it might be interesting. I have a strong feeling I'll be changing this barrel at some point soon after the build, but I'll have some data when it's over.
    Yes, .093 is very big for even a 16" mid gas with heavy spring and buffer. Never mind a CAR gas.

    An insertable gas port is probably the best way to make that barrel work properly.
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
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  4. #114
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    Quote Originally Posted by SPQR476 View Post
    Well, I said "what the heck" and put the barrel on last night. I have a hard time believing that this will work out to any degree of satisfaction, but it might be interesting. I have a strong feeling I'll be changing this barrel at some point soon after the build, but I'll have some data when it's over.
    Any updates on this Duane?

    Did you ever shoot this barrel with a ridiculously large gas port?
    Last edited by Clint; 04-12-13 at 14:58.
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  5. #115
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    Quote Originally Posted by AR15barrels View Post
    but 9 times out of 10, it's not even the gas port size...
    Words that should be carved over every bench used by visitors to this forum.

  6. #116
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    Quote Originally Posted by Clint View Post
    Yes, .093 is very big for even a 16" mid gas with heavy spring and buffer. Never mind a CAR gas.

    An insertable gas port is probably the best way to make that barrel work properly.
    Holy smokes! My 14.5" Middy runs about perfect with an .080"... my other 14.5 middy is a little fussy with an .076".

    .093" might be ok on a 16" with Rifle length gas, but Wow... not much else.
    "You people have too much time on your hands." - scottryan

  7. #117
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    Quote Originally Posted by markm View Post
    .093" might be ok on a 16" with Rifle length gas, but Wow... not much else.
    0.093" is perfect on a 20" rifle gassed bull barrel.
    0.093" will be too small for a 16" rifle gassed barrel unless it is a 17 Remington, 20 tactical or 204 Ruger.
    Randall Rausch
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  8. #118
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    What increase "decrease" is needed to make an actual change in the gas pressure? It seems you aren't going to increase the hole a thousandth then check operation?

  9. #119
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    Quote Originally Posted by markm View Post
    Holy smokes! My 14.5" Middy runs about perfect with an .080"... my other 14.5 middy is a little fussy with an .076".

    .093" might be ok on a 16" with Rifle length gas, but Wow... not much else.
    Quote Originally Posted by SteveS View Post
    What increase "decrease" is needed to make an actual change in the gas pressure? It seems you aren't going to increase the hole a thousandth then check operation?
    You can see the function change with 0.003" gas port size changes if you know what to look for.
    Randall Rausch
    AR15 Barrel Guru
    California Precision Rifle Club founding member

  10. #120
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    Thanks that is a tiny increase . What is the increase due to gas erosion after X amount of rounds fires? I would imagine the rate of erosion has to vary depending on many factors but a ball park figure?

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