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Thread: Cutting a 14.5 BCM to 12" Midlength?

  1. #1
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    Cutting a 14.5 BCM to 12" Midlength?

    I have a 14.5" BCM midlength upper that I want to cut to 12.0" and run it suppressed always.

    Has anyone done this before? Will a midlength gas system work on a 12" barrel with a can? I would think the Can might add enough to it to make up for the 2" barrel loss? Maybe? I have seen Faxons 11.5" midlength barrel but I'm assuming you'd need a good adjustable gas block. I would like to keep my upper as factory BCM as possible.

    Am I really better off selling this upper and getting an 11.5 carbine one?

    Thank you!

  2. #2
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    I am not sure why you would want to do this. I think you would be inviting a problem that does not need to be there.

    There have been some specific barrels made in 11.5" and 12.5" with mid-length gas, but from what i understand it was done to reverse engineer a gas pressure for a specific load and a specific suppressor, and the gas port size was... well... different, and nobody I know wanted to talk about the specs. Some black ops stuff or perceived proprietary formula. Faxon was the one I know about with the 11.5." That sounded crazy to me. It could only work with a giant gas port, or suppressed, as there is just not enough dwell time to get the pressure out otherwise.

    I guess I also don't understand your desire to keep it factory BCM. At the end of the day, BCM has a decent barrel, but it is not hard to improve upon a BCM barrel. Everyone I talk with who shoots under 14.5" points to Colt. I think DD makes a decent 10.3", but I have been corrected a few times. I also think BCM makes a decent 14.5", and have been corrected again. All eyes point to Colt, when running suppressed under 16." You can get a Colt in 11.5" and run it suppressed pretty easily. Or, if you want to stick with BCM, buy a 11.5" BCM barrel, but first ask them about their experience running it suppressed. I have no experience with BCM at 11.5." Sell your 14.5" used.

    There is a cost to cutting and threading, and with the price of barrels coming down, why not get the right tool?

  3. #3
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    While I have a 11.5" BCM, I have never run it suppressed. I do believe that it would be best to sell your 14.5" (if you must sell it) and go with the 11.5" or 12.5" BCM upper if you want to stay with BCM. So 1/2 shorter or 1/2 longer than your desired 12".
    I look forward to seeing how your journey progresses.

    Onward and upward!!!

  4. #4
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    Quote Originally Posted by VT RAIDER View Post
    While I have a 11.5" BCM, I have never run it suppressed. I do believe that it would be best to sell your 14.5" (if you must sell it) and go with the 11.5" or 12.5" BCM upper if you want to stay with BCM.
    I think your BCM 11.5" is a carbine, and not a mid-length.

  5. #5
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    Quote Originally Posted by longshot2000 View Post
    I think your BCM 11.5" is a carbine, and not a mid-length.
    That is correct it has a carbine length gas system... apologies, I did not mean to imply it was a mid length...


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    Thanks,
    Yeah I have zero need for a 14.5 upper. I got this one for free and its still brand new in box just sitting there. Figured rather than deal with selling it I'd just chop it down to 12" throw can on it and be done. I have an extra Gemtech TREK-T, so might as well mate it to something. I run an 11.5 BCM suppressed now and its perfect. Yes thats a carbine length gas though. I also thought maybe a miglength suppressed would be smooth??
    Basically I'm just looking for the fastest and easiest way to make this upper shorter so I was wondering if anyone has done it to a midlength. I don't want to spend much time on this project. I have enough days messing with adjustable gas blocks and what not.

    I'm willing to be a guinea pig and try it, just as long as a few people don't come on here first saying they've already done it and it doesnt work. That would be a waste.

    I like Colt, but I love BCM.
    Last edited by backpacker; 09-12-17 at 18:48.

  7. #7
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    Quote Originally Posted by longshot2000 View Post
    I am not sure why you would want to do this. I think you would be inviting a problem that does not need to be there.
    I worry that you are probably right.

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    I would think, by now, that someone would have gotten them math right and had it working. But alas, it seems now one has. Mid length carbines have been mainstream for what, 5-7 years and with the current pace of development one of the big name companies would have gotten it right. People would be singing their names to the heavens.
    AQ planned for years and sent their A team to carry out the attacks, and on Flight 93 they were thwarted by a pick-up team made up of United Frequent Fliers. Many people look at 9/11 and wonder how we can stop an enemy like that. I look at FL93 and wonder, "How can we lose?". -- FromMyColdDeadHand

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    http://www.m4carbine.net/showthread....Build-AR-Forum

    To all concerned.

    The custom build area is a place to show off/discuss and ask questions and get feedback about your completed custom build (this means a completed AR that is functional and already completed). If you are going to post pictures of your build, please post a complete picture not just your parts, partial lowers, etc....

    Also, buying an upper separate and then a lower and throwing them together does not constitute a custom build. It would be nice if you took time to explain how you came to your decision and explain your set up. Thanks.

    If you do not follow the guidelines and your post disappears it's probably because it was moved to the trash or deleted.



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