Freebore in the RUM family

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by hemiford, Jun 8, 2014.

  1. hemiford

    hemiford Well-Known Member

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    Does anyone know how much freebore Remington puts into their
    RUM barrels ? I think I read .400 on the 7mm and the 300, but I
    don't know about the 338 or 375. I would think it would be different.

    I'm considering ordering a 375 barrel.

    I think I have a handle on how freebore potentially affects both accuracy
    and safety (overpressure), and the safety consideration concerns me more.

    When SAMMI specs a chamber, does it include a freebore spec ?

    Or is freebore a custom variable that must be reamed in specially ?

    I must learn how to order the barrel properly.
     
  2. Edd

    Edd Well-Known Member

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    The SAAMI specs include freebore but you can order a reamer with whatever freebore you want.

    SAAMI specs

    7mm RUM .400"
    300 RUM .110"
    338 RUM .160"
    375 RUM .175"
     
  3. hemiford

    hemiford Well-Known Member

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    Wow. Thank you Edd.
    I do not understand the pattern there at all. There must be some rationale.
     
  4. Edd

    Edd Well-Known Member

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    Don't confuse yourself with logic. I've done a lot of research on free bore. I don't think it is a precise number that is chosen by some sophisticated scientific calculation.
     
  5. hemiford

    hemiford Well-Known Member

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    OK. I still like to look for patterns, perhaps I could write you a long boring PM
    and see if it makes any sense. I have a feeling freebore involves the maximum
    grainweight bullet like that is most likely to be fired.

    By chance, do you know the freebore for 7stw ?
     
  6. Edd

    Edd Well-Known Member

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    .200"