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Thread: Custom projectile BTO difference

  1. #1
    Join Date
    Jan 2017
    Location
    Australia
    Posts
    35

    Custom projectile BTO difference

    I purchased 1000 6mm custom projectiles well known US maker, they measured BTO .4050 give or take .0001 or 2. I just received a second lot of 1000 in 2x 500 box's. 1 box BTO is .3930ish and the 2nd box measures .3950ish. Living in Australia i have no say in what type of box's the exporter send me. I would have preferred a 1000 box but may be 2x500 is all he had. To be honest im a bit disappointed in the difference in BTO measurements, is it normal for there to be such a difference? I guess i just have to seat these ones out a bit further and hope the tune doesn't change much.

  2. #2
    Join Date
    Jun 2008
    Posts
    487
    Different lots of jackets can vary length of bearing surface or bto as you say

  3. #3
    Join Date
    Feb 2003
    Location
    Tennessee
    Posts
    5,163
    I wouldn't give this a second thought. Would not mix them together but that's about it.

    Let us know how they shoot - box to box.

    And....you do have a say!

  4. #4
    Join Date
    Jan 2017
    Location
    Australia
    Posts
    35
    Quote Originally Posted by Wilbur View Post
    I wouldn't give this a second thought. Would not mix them together but that's about it.

    Let us know how they shoot - box to box.

    And....you do have a say!
    I suppose i do have a say Wilbur, thats just a silly comment on my behalf, next time i'll ask for a 1000 count box's only.

  5. #5
    Join Date
    Dec 2017
    Posts
    574
    SINGLE LOT, single box. else he might just pour 2 lots in one box..ouch.

    Quote Originally Posted by michaeljp65 View Post
    I suppose i do have a say Wilbur, thats just a silly comment on my behalf, next time i'll ask for a 1000 count box's only.

  6. #6
    Join Date
    Jun 2010
    Location
    USA
    Posts
    542
    Presuming the same point-die, to expand upon George's and Wilbur's take, and NOT altering the seater-stem: the only thing that will change, with varying B-O, is that the bullet base will go into, or out of, the case neck roughly the thickness of a business card. The "seating-depth", or, relationship of the ogive to the lands will not change - again, presuming the same point die. Just load 'em and shoot!RG

  7. #7
    Join Date
    Feb 2006
    Location
    Wilcox, PA
    Posts
    78

    Reply from bill b

    1. There is a difference in core seating pressure -- or --
    2. there is a difference in the material in the jacket will change that or change ojive measurement

    Bill

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