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Thread: Can you cut down a M4 config barrel to 11.5"?

  1. #1
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    Can you cut down a M4 config barrel to 11.5"?

    Since I don't have access to my guns at this moment, I can't take a measurement & answer myself.

    Is there enough material on the M4 conf barrels to allow cutting to 11.5"?

    I didn't know if the cut for the 203 would allow for this.

    I want a quality mil spec barrel & am tired of waiting on possible solutions nor do I want to pay $400+ for a new Colt barrel. I have run into some Colt M4 barrels with welded FH's & including chop & rethreading would be less than $300.

    I'm open to suggestions.

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    M4 cut barrels work best at 12.5". That puts the FH just in front of the 203 cut.

    You might be able to get it cut to 11.5, but it'd look weird as hell.
    "You people have too much time on your hands." - scottryan

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    This is actually slightly less than 11.5", something like 11.3" or so. haven't measured it precisely.

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    The original MK18(CQBR) is a cut down M4 barrel to 10.3in so yes it can be done but you will have to open up the gas port to .069-.071. The 12.5in I believe comes from the fact the that it will give you 5in of dwell time and that is considered to be the minimum and still have a large operational envelop for reliable function. I know you can get the short ones to run guys do it all the time but even the MK18 can have trouble in colder weather. The more dwell time will also allow for use of a larger variety of ammo as well.

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    Yeah. Someone here posted that LMT had cut several of their 14.5s down to 12.5 for his unit. They ran good with no port modifications.
    "You people have too much time on your hands." - scottryan

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    You aren't saving money buy cutting down a M4 barrel over buying a factory 11.5" outright.
    "Not every thing on Earth requires an aftermarket upgrade." demigod/markm

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    Quote Originally Posted by scottryan View Post
    You aren't saving money buy cutting down a M4 barrel over buying a factory 11.5" outright.
    Only if I can get the barrel in the low $200 range. I have a line on a complete Colt Commando upper & I think im going that route. Im just getting tired of waiting for what seems to never be available or priced thru the roof.

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    Quote Originally Posted by VLODPG View Post
    Only if I can get the barrel in the low $200 range. I have a line on a complete Colt Commando upper & I think im going that route. Im just getting tired of waiting for what seems to never be available or priced thru the roof.


    It is better to buy a factory barrel at any price range.

    You start with a $350 Colt M4 barrel.

    You chop this and thread for ~$100 and do any gas port work/refinishing.

    Now you are up to $450 in this project. You are left with a cut down barrel that is worth $125 at the most.

    So you are basically out ~$300.

    The only time when you need to be modifying a barrel is for a custom length.
    "Not every thing on Earth requires an aftermarket upgrade." demigod/markm

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    We shoot some ICE/Customs ar's last year and they had there barrels cut down. They went from a AUG to Colts with cut down barrels. I was told that they could only get 55bt to stablize out of them every thing else keyholed.

    Dave

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    Quote Originally Posted by kittyhawk View Post
    I was told that they could only get 55bt to stablize out of them every thing else keyholed.
    Barrel length wouldn't have anything to do with that. Twist rate or a poor job of barrel chop might though.
    "You people have too much time on your hands." - scottryan

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