Sort by bearing length and by weight?

Discussion in 'Reloading' started by esshup, Jan 31, 2012.

  1. esshup

    esshup Well-Known Member

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    I'm trying to fine tune my reloading. I've purchased the Buhay tool and I'm in the process of sorting my bullets into .001" groups. Do I need to sort by weight too, or is it not necessary? If yes, then what weight variance should each group have?

    FWIW, it's for one of Kirby's 7mm AM's.

    Is .001" groupings of the bearing surface getting too anal?

    I went back thru the sub-forum to 2007, and saw that bearing surface was more important than weight, but no numbers or % was given for determining how to group the bullets that were sorted.
     
  2. Gene

    Gene Well-Known Member

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    What brand bullets? Some are more consistent than others.

    I sort them out and use any that exceed 3 grains difference for sighters.

    Bearing surface measurement is more important for good accuracy. Again, I cull out those that exceed .001".
     

  3. Boss Hoss

    Boss Hoss Well-Known Member

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    I have used the Buhay tool for many years and use SMK's only and I do not sort by weight. Found that it was a waste of time..
     
  4. esshup

    esshup Well-Known Member

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    Wildcat 7mm bullets. I arbitrairly set the indicator at .000" and have groups of bullets that are as follows: -.002", -,001", .000", +.001", +.002", +.003"

    There could be a varience of .001" within those groups, if a bullet was -.0004" or +.0004" from those numbers, it went into the same group. The biggest groups are .000" thru. +002", but the other groups aren't that far behind in numbers. I've only sorted 300 bullets so far.

    I randomly grabbed bullets out of the groups and re-measured, and my measurements didn't change, so I'm confident that my measuring procedure is correct and repeatable.

    I have 175g SMK's and 180g Bergers that I will be measuring too.
     
  5. Mikecr

    Mikecr Well-Known Member

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    I don't think bearing variance could be proven to make any difference at all.
    For one, your datums aren't qualified as consistent(ogive radius, base angle).
    And if your measuring base to nose, then base length would need to be accounted for differently.
    Second, unless you account for each drag component, summed to contribute to BC, you could not know if bullets match in BC regardless of individual measures.
    Third, without RADAR or atleast an accoustic chronograph, you cannot measure the tiny bullet engraving length affects to MV.

    And as far as weight, if your bullets vary in weight enough to affect anything, you are using horrible bullets. All parameters would then be suspect so rake em into a trash can.
    Pull out the wallet and buy the best bullets you can.
     
  6. esshup

    esshup Well-Known Member

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    Mikecr, then what bullets do you suggest (that are available)?

    If you knew what a Buhay tool was, then you wouldn't have made some of the other comments.
     
  7. Boss Hoss

    Boss Hoss Well-Known Member

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    I hope you are kidding. Len has told me not to put cold hard data out to make people look bad but for God's sake do the due diligence before you type..... Find out about the subject before making a formal statement. I am sorry I could not let this statement go unaddressed.

    Bearing surface equals pressure. I have posted paragraphs about this in the past and I am sure others have as well.

    Read this thread: http://www.longrangehunting.com/forums/f28/bullet-comparator-sorting-bullets-57452/
     
    Last edited: Feb 1, 2012
  8. BountyHunter

    BountyHunter Writers Guild

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    It was proven repeatedly ten years ago with the 300 great SMK. No other changes other than sorting by ogive cut vertical by as much as 50%.

    Before sorting the 338 was not competitive. I have seen .017 variance in one box of 100 bullets.

    Try it and you will not go back!
     
  9. esshup

    esshup Well-Known Member

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    Mickcr, I thought about my answer and it may have been a bit harsh.

    If I'm not building my own bullets, I don't have any control over the consistency of the ogive radius or the base angle. What else can I do to ensure the most consistent reloads? I thought I purchased bullets that the 7mm shooters here have had good results with. If their results haven't been good, then why are the Wildcat bullets known for being the best ones for that chambering and distance (7mm AM and 1K+), provided that they are available?

    Of the items that you mentioned, what would have the most influence on group size at 1K and beyond? Would that have more influence than bearing surface or less?

    Can you tell me where a person can buy measuring equipment that is cost effective for measuring the ogive and base angle when only loading 1,000 or so rounds?

    I'm not a benchrest shooter, nor have I been in the long range game for very long. I'm trying to learn as fast as I can so I can shoot to the best of my ability. I figure that if I use the best components, assemble consistent ammo, have good quality equipment, then the rest is solely upon my shoulders to do the best job that I can do.
     
  10. Mikecr

    Mikecr Well-Known Member

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    I do have a Buhay/Tubbs/JB comparator, and a more accurate tool of my own design. I have seen no qualified evidence of bearing variance affects to MV, only internet inferences that so far hold little basis.
    I see no 'cold hard data' from anyone, and my own testing indicated no benefit with consideration of bearing variance only.
    I think my input is valid as any.
    Also this is not 'sorting by ogive' as that is done by a completely different tool(B.G.C and/or my mine).

    On bullet weight(only), .5gr variance on a 140gr VLD might shift POI .07moa(~3/4") @ 1Kyd. Worth weighing hell that's easy enough. But variance around and beyond that(with that bullet) would make other things about the lot suspect IMO.
    I don't see that much with Bergers, JLKs, Jayners, BIBs or Lapuas.
    Now with big heavy .338cal bullets(like a 300smk) you could see more weight variance of coarse, but it's affect on BC would be half as much compared to same with a 140vld.

    esshup, I'm not out to dissuade your efforts, and I couldn't tell you what to do, other than to consider what it is you're actually doing.
    For all you know, bullets sorted to match in bearing, or weight, won't match in BC.
    Which will have a larger affect downrange?
    Well it's my contention that understanding this matters.
     
  11. Edd

    Edd Well-Known Member

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    Have any of you ever taken a sample of bearing surface measured bullets then pushed them thru a short barrel stub and remeasured them? I'm curious if the variance remains consistent. For example, if you have three groups of 5 bullets will the bullets still be grouped the same and the bullets in each group still be equal lengths. I've got my doubts.
     
  12. Boss Hoss

    Boss Hoss Well-Known Member

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    Pushing a bullet without the tremendous pressure associated powder ignition and the subsequent forces associated with it are much different that attempting first ensure the bullet is concentric in the bore and hammering it through to see what happens to the bullet. Yes sorting by bearing surface does work but like everything else in precision long range shooting it is only one of a host of actions that must be completed to ensure consistent results.
     
  13. Edd

    Edd Well-Known Member

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    I don't remember saying anything about hammering it through. I believe the word I used was "pushed".
     
  14. Scot E

    Scot E Well-Known Member

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    I am beginning to get a bit nervous here. Why would we not want cold hard data being presented, especially by some of the best and most knowledgeable on this site? What is the point if guys can't come here and learn real facts about what works vs. what is just a bunch of fluffed up opinion?

    Scot E.