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Thread: Fitting a bolt to a barrel

  1. #1
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    Fitting a bolt to a barrel

    I've seen it mentioned a few times in passing on the forum and else where. There is a youtube video of a Noveske shop tour where they mention fitting bolts to barrels. Grant from G&R mentioned it in his varmit rifle build thread. Can someone advise what this entails and how it is accomplished.

    Thanks for any info.

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    Irrelevant info, ignore this post
    Last edited by Scorpion; 11-22-12 at 09:15. Reason: Removed post

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    Gotcha. But all bolts are not going to give the same headspace reading. For instance I sent my noveske upper in for a feeding issue later id'd as a weak buffer spring. I sent in my BCM bolt that I bought as a replacement/spare. The guy with Noveske said that the BCM bolt barely passed headspacing on the loose end and the Noveske bolt was tighter and would provide better accuracy.

    So what does fitting require. Going through a box of bolts finding one that fits tighter on a particular barrel? Is the bolt lapped into the barrel extension?

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    You got it. There is no lapping done and there's nothing an end user can do to fit a bolt to a barrel other than what you've mentioned.

    Quote Originally Posted by Serpico1985 View Post
    So what does fitting require. Going through a box of bolts finding one that fits tighter on a particular barrel? Is the bolt lapped into the barrel extension?
    Last edited by Eric D.; 11-18-12 at 22:32.
    B.A.S. Mechanical Engineering Technology

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    Thank you Eric D.

    So is the following correct?

    -The headspace is set when the barrel is installed in the upper receiver.

    -Any bolt that is in spec will operate in a correctly built/assembled rifle

    -There is a small but acutal bennifit from choosing a bolt that is in spec but at the tighter end of the spec and in theory should have a longer functioning life and/or provide better accuracy vs a looser fitting bolt.


    Is anyone able to discuss the acutal bennifit in accuracy provided by a "fit bolt".

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    What would be the proper gauge to measure this and how would you employ it?

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    Quote Originally Posted by Scorpion View Post
    When first assembling a carbine, the bolt and barrel extension will most likely be a bit of a rough fit due to manufacturing tolerances. As the rifle is cycled and used, the two parts will wear together and thus become pretty much mated to each other (which is one reason why you may be told not to switch bolts between rifles; the other is any headspace issues that may develop).

    At least that's how I've interpreted it.
    This has nothing to do with fitting a bolt to a barrel.


    C4

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    Quote Originally Posted by mtdawg169 View Post
    What would be the proper gauge to measure this and how would you employ it?
    Noveske came up with a standard fitting for bolt to barrel. We purchased gauges from them and follow their protocol when fitting.


    To date, every single gun that I have fitted a bolt to a barrel has shot UNDER 1" groups.

    Do I think it makes a HUGE difference? No I don't. It is one of the steps that I follow religiously though when building a precision rig and to date, have never been let down.



    C4

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    The "fitting" is just a smaller than MIL-SPEC headspace range that we keep. It's mainly done by controlling headspace very precisely when making barrels, then checking headspace during assembly with gauges that have a smaller window between Go and No-Go that M16/M4 standards.

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    Quote Originally Posted by Todd.K View Post
    The "fitting" is just a smaller than MIL-SPEC headspace range that we keep. It's mainly done by controlling headspace very precisely when making barrels, then checking headspace during assembly with gauges that have a smaller window between Go and No-Go that M16/M4 standards.
    So what you're saying is, I'm SOL!

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