Excessive bullet seating force despite using mandrel expander

Tokay444

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  • Jun 24, 2019
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    I don’t even watch SD. If ES is low, SD can’t be anything but low.
     

    Feniks Technologies

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    I don’t even watch SD. If ES is low, SD can’t be anything but low.

    Still, single digit ES is all but impossible long term.

    Also, ES is a far less valuable number.

    You can easily have something throw off your ES in what can be a much better performing load in the long run.

    I used to subscribe to the same thought process until I became more educated with sd and es in detail.

    There’s a reason most all statisticians will use SD and not ES.
     
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    Gohring65

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    Still, single digit ES is all but impossible long term.

    Also, ES is a far less valuable number.

    You can easily have something throw off your ES in what can be a much better performing load in the long run.

    I used to subscribe to the same thought process until I became more educated with sd and es in detail.

    There’s a reason most all statisticians will use SD and not ES.
    This is my method of understanding as well.
     

    Feniks Technologies

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    This is my method of understanding as well.

    Here’s an example of some chrono data from a 6gt.

    34.6gr: Sd: 5.1 Es: 13
    34.8gr: Sd: 6.7 Es: 15
    35.9gr: Sd: 4.7 Es: 13

    Well, if we just looked at ES, we’d think these are all very close. One may even think 34.6 is same because it had the same ES of 13 as the 35.9.

    However, statistically we know that 99.7% of shots will be within 3 standard deviations each way.

    That means 6x your SD.

    Now, that means:

    34.6: ES: 30.6
    34.8: ES: 40.2
    35.0: ES: 28.2

    All of a sudden that 15es in the middle that looked very close to the others is much further apart.
     
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    There are some load development methods that look at ES clusters for “nodes.”

    If you don’t multiply your sd (and it needs to be statistically significant sd) by 6…… there’s a very good chance you’ll have some bad clusters.