barrel twist

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by xander, Sep 18, 2004.

  1. xander

    xander New Member

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    Sep 17, 2004
    I am having a 338 ultra mag built on a Ruger #1 with a 28 in. bbl. I am going to use 200-210 grain bullets.Everyone says I should use a 1-10 twist.I did the Greenhill formula to calculate the twist rate for the bullets I'm planning to use and it comes to 1-12 or a tad slower.I won't be using any bullets over 225 grs. max.I would appreciate some suggestions for those of you that use a 338 UM,particularly those of you that use lighter bullets. thanks.
     
  2. Guest

    Guest Guest

    I don't have a 338 RUM but I do have a
    338-06 Ai , it has a 1-12 twist and shoots the 200gr Nosler Ballistic tips and 210gr Nosler Partitions great.
    My velocity is just over 2500fps out of a 22" barrel , I would think that the faster 338Rum would use maybe a 1-13 but why risk it ? Your not gonna realy gain any velocity by going to that much slower twist.
     

  3. ZERMEL

    ZERMEL New Member

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    Aug 9, 2004
    Ruger#1.
    Ther Greenhill formular is not all that reliable, it overstabilizes by a considerable margin. You should use a constant of about 180 rather than the 150. I would use a 1-12" twist because of the higher velocity which the Greenhill formula does not address.
    The faster the bullet the less twist you need.
     
  4. xander

    xander New Member

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    Sep 17, 2004
    Thanks for the input.I think I will go with the 1-12 twist.This rifle is intended as an open country rifle.I think the lighter bullets will suffice.