Sorting bullets: Base to ogive vs length of bearing surface.

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by BountyHunter, Apr 16, 2003.

  1. BountyHunter

    BountyHunter Writers Guild

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    First off no flames here, just honest request for info from anyone that has tested. Always willing to try something new that is better way of doing business.

    I have seen/heard of two ways of measuring/sorting bullets.

    1. Base to ogive
    2. Length of bearing surface. Ogive to back of bearing surface.

    My personal experience is that length of bearing surface has shown to be key factor in sorting boattail bullets.

    I have seen two methods used for determining length of bearing surface.

    1. Two stoney point comparators ($40)attached to dial caliper blade with ogive inserts put in them. The base comparator comes up to the back of the bearing surface and the front measures at the ogive. This gives you a standard measurement to use as "length of bearing surface".

    2. Bill Shehane sells a tool ($275)that is built off a J & P Granite checker device, extra calibers are $75. His tool uses the granite checker, dial indicator with a caliber nose piece attached and a milled out base that the bullet sits in. Same thing gives you a length of bearing surface reading. Many LR and BR shooters swear this is a valid method and their testing supports that. I just bought the J & P tool ($50) and having gunsmith make the base and nose pieces for my calibers.

    Not sure why you would measure length of a boatail that does not contact a case neck or barrel as the base to ogive method uses. Now if it is a flat base bullet, then by all means measure that.

    What is purpose of measuring length of a boattail that touches nothing? Bullet seats off the ogive so seating depth will not be effected.

    What does this method show you that is more accurate than length of bearing surface?

    BH
     
  2. 4mesh063

    4mesh063 Well-Known Member

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    Bounty,

    I just had a conversation at the club about this very subject and between my own findings and the findings of the person I talked with, I'd say, weigh the bullets and make sure they are somewhere close to what they should be and shoot em.
     
  3. BountyHunter

    BountyHunter Writers Guild

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    Used to believe that myself, but I have proven that after weighing into lots if you sort by length of bearing surface, groups will smaller. Not so much large difference with custom bullets like JLK and Berger, but a marked reduction in groups with Sierras. In fact, I have found the the sorting by length of bearing surface is more important than sorting by weight. Tried it both ways. Someone else may test and find different.

    Just heard other guys saying, sort by base to ogive. that makes no sense to me and just wondering what difference measuring something that touches nothing(case neck or barrel lands) has based on their testing.

    BH
     
  4. 4mesh063

    4mesh063 Well-Known Member

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    I'd bet they mean boattail to ogive like what you're thinking. The base to ogive is meaningless. To "Accurately" measure them would be pretty difficult.

    I sorted and found 15 berger bullets for my last match to .000025" (25 millionths). They shot all over hell so I guess I have bigger issues than bullet size!
     
  5. Chris F

    Chris F Active Member

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    Greg Siegmund, maker of the Clinch River bullets that are catching fire with the long range crowd is a big proponent of sorting by "wheel base" as he calls the bearing surface. Says it makes a measurable difference on the target.
     
  6. Tim Behle

    Tim Behle Well-Known Member

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    Is it worth the time to sort by both weight and bearing surface? Or would I be better off just sorting by length of the bearing surface, and not worry if there is a couple of tenths difference in weight?