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Thread: BCM/DD 14.5 Gas Port Sizing

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    BCM/DD 14.5 Gas Port Sizing

    There are already a lot of BCM vs. DD threads, but I would like to ask a more pointed question:

    Can anybody compare the gas port sizes of the 14.5 middy BCM and 14.5 middy DD uppers? I hear constantly about how smooth the BCM shoots, but not much about the DD. I assume this is partially a function of BCM’s small gas port size; I would like to know how the DD compare. In theory, assuming they have the same size gas ports, they should both run equally smooth when setup with the same length gas systems, buffers, muzzle attachments, etc. Thanks for the help.

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    I am curious as well. I've been trying to make the very same decision. Any help would be appreciated.

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    delete
    Last edited by tylerw02; 11-10-10 at 17:44.

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    Is there a trade off between "soft shooter" and reliability? The reason i ask is because i would think that if you had two of the exact same middies with 1 having a smaller port that even though it would be slightly softer shooting in an already soft 5.56 it would also be more prone to short stroking when its dirty or weak ammo etc... Again, this is a question not fact lol

    I have also been wondering the same question as you and haven't had any luck...in the meantime it got me thinking of the question above...I would be glad to measure for you but i have a DD carbine barrel. Hopefully sum1 will have the specs...

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    Quote Originally Posted by CQC.45 View Post
    There are already a lot of BCM vs. DD threads, but I would like to ask a more pointed question:

    Can anybody compare the gas port sizes of the 14.5 middy BCM and 14.5 middy DD uppers? I hear constantly about how smooth the BCM shoots, but not much about the DD. I assume this is partially a function of BCM’s small gas port size; I would like to know how the DD compare. In theory, assuming they have the same size gas ports, they should both run equally smooth when setup with the same length gas systems, buffers, muzzle attachments, etc. Thanks for the help.
    Your not going to get any info on this as very few people are going to have both barrels, and even fewer are going to have the ability to measure the GP's.



    C4

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    I ran across something the other day but I cannot remember where... It said the DD gas ports are .075 inches. I can't cite the source so it may be incorrect.

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    CQC.45,

    I've got a DD 14.5" Mid-length Lightweight and the gas port is .625" on that one. I've also got a ruined (bulged) BCM 14.5" Mid-length barrel hanging on the wall of a friend's gun room that I can measure, but it will be sometime later this month before I can get to it. I wrote down all the specs on that BCM barrel when I did the build but it's on a yellow legal pad somewhere. I need to find it and put all those specs in my database anyway so I'll see if I can find it tomorrow.

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    Quote Originally Posted by D. Christopher View Post
    CQC.45,

    I've got a DD 14.5" Mid-length Lightweight and the gas port is .625" on that one. I've also got a ruined (bulged) BCM 14.5" Mid-length barrel hanging on the wall of a friend's gun room that I can measure, but it will be sometime later this month before I can get to it. I wrote down all the specs on that BCM barrel when I did the build but it's on a yellow legal pad somewhere. I need to find it and put all those specs in my database anyway so I'll see if I can find it tomorrow.
    Your gas block seat might be .625" (aka 5/8"), there's no way in hell your gas port is 5/8".
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    Quote Originally Posted by gotm4 View Post
    Your gas block seat might be .625" (aka 5/8"), there's no way in hell your gas port is 5/8".
    Sorry, I was going by the data on the DD site.

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    Quote Originally Posted by D. Christopher View Post
    Sorry, I was going by the data on the DD site.
    DDs gas ports for CAR gas guns (14.5-16") is .0625"
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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