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  • Need a hand to validate some info Re CBTO

     james updated 1 year ago 2 Members · 3 Posts
  • james

    May 16, 2021 at 7:53 am

    Hi guys I’m writing the script for a video on CBTO for my chanel but could use a hand validating some info.

    I believe that not all CBTO tools use the same dimensions, I have the Hornady bullet comparitor and the 308 collet measures .2960 inches. If anyone has one made by another manufacturer could you please kindly measure the inside diameter of the 308 collet and list it below.

    Thank you in advance.

  • HumidNut

    May 16, 2021 at 7:53 am


    My example of a Hornady insert measures .2980″

    My example of a Sinclair insert measures .2940″

    Two mfg, different measurements.
    Same mfg, two different measurements as well, it seems.

  • ClarenceWagner

    May 16, 2021 at 7:53 am

    CBTO tools are for being able to measure consistently for the loads worked up using that exact tool. It’s about using that exact tool to “compare” repeatable results, which should have less inherent variation than using COAL. Which is why some people use a seating comparator, essentially does the same thing only it’s measuring off the shoulder of the case. It’s really just measuring from a know point to a know point. Increasing precision of the bushing diameter wouldn’t change much since the whole goal is really to compare a specific part along the ogive (most of the curved portion of the projectile is the ogive as pointed out by the article). All it would do is make each tool more likely to come up with similar measurements across that brand of tool. Which is not really that useful. It is ill advised to use the same CBTO across various tools. If you switch tools all you do is measure completed rounds validated by the old tool and using the new tool write the new number/s down to be used with the new tool. (example: I have a hornady my friend has a Forster I have two sets of numbers one for my tool and one for his they are both correct measurements, but they are not the same numbers.) If you use the comparator to measure your projectiles ogive to base, you’ll most likely find variance especially in the cheaper projectiles, so much that you can visibly see it. Fclassjohn and Boltactionreloading each have done a video on it (I recently watched boltaction so it was easier to find)

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