reciever to barrel tolerances

Discussion in 'Gunsmithing Forum' started by mattybock, Jun 26, 2012.

  1. mattybock

    mattybock New Member

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    let's say I had to fit a barrel to a reciever. What would the acceptable tolerances be for the fit? Numerical figures, please.
    How loose is too loose and how tight is too tight?
     
  2. BillM

    BillM Active Member Supporter

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    Interesting question from someone all primed to launch their own
    firearms manufacturing business.

    What kind of fit? Press? Threaded? Slip? Interrupted thread?

    Tolerance between what parts?
     

  3. mattybock

    mattybock New Member

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    For this - let's use the mauser 98 as an example, being threaded with a non-interupted thread. With the barrel being 4140, and the receiver being made of the same - what would the tolerance be for safety?
    or- how tight is too tight?
     
  4. BillM

    BillM Active Member Supporter

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  5. hiwall

    hiwall Active Member

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    There is no real tolerance. It can not be loose at all. I guess I never had the ability to see how many foot-pounds of torque I used to seat the barrels. I just turned them in tight. I know I got some tighter than others.
     
  6. mattybock

    mattybock New Member

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    I'm only using the mauser as an example. And according to the comment right about mine the barrel cannot be loose. I figured that bit, so I'll rephrase the question as I should have written it in the beginning...

    at what measurment in inches (.001), does a threaded part made of steel become noticeably harder, or very difficult, to put in?
     
  7. mountainman13

    mountainman13 New Member

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    Do yourself a favor and just ask your question straight out. What are you working on? If you just say, how hard do I have to torque an AR barrel on? You will get an answer much faster.
     
  8. Millwright

    Millwright New Member

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    MB,

    If I understand your question correctly, all the info you need regarding thread form/pitch/buttress-root clearance, etc. can be found in the Millwrights & Machinists Handbook. OTOH, "torque" - as measure of "tightness" - would depend upon a number of variables, not least of which would be the material/style of receiver the barrel is being threaded into. >MW