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#109 – Modern Solvers and Drag Explained

#109 - Modern Solvers and Drag Explained

00:36:33 | This week on the Science of Accuracy: Bryan and Francis deep dive into the history and evolution of modern ballistic solvers and drag modeling.  This episode answers common questions and misconceptions about how solvers function, including the G1/G7 drag models, drag as it relates to speed and more. We cover all the bases in this episode!

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  • Ivan Bukvic says:

    Use what champions are using is smetimes easier said then done. In Europe those choises are not available most of a time. And when they are, it is a limited quantity sold quickly, costing fortune.

    Some of us have to look at alternatives. LOT to LOT variance is not a big deal with most of alternatives. One I am using is very consistent LOT to LOT. Problem is a change in a production if it happens.
    For example LOTs I am using now (3 LOTs checked) are completly different from the LOTs I was using before. Year 2022 look as changing point.
    Difference is so huge that indeed this is a different bullet. Not only that drag is significantly lower but stability requirement too. According to McCoy McGyro minimum twist is slower now. Thus static stability factor higher.
    Fact I am pointing them is making that difference even higher and more complicated.
    But the new LOTs performs much better then the old ones (very close if not equal to champions choice), so I will continue to use.

    Now I have to calibrate ballistic firing solution. With a different bullet then entered into that solution. Using only MV. Good luck with that.

    I believe that situation as described is more frequent then it is discussed. And that many shooters having unsolvable problems with calibration are actually shooting the different bullet from the one in the calculator. Yes, titles on a box and in calculator matches, but not the bullets. Just they are not so detailed to notice the real problem they have, but blame the calculator, scope, skills, 3 shots group center……. instead of not published change in a bullet production resulting in a basically new bullet.

    For those situations, admiting that altering some other inputs beside MV might be a good idea. Like BC and bullet lenght, followed by a MV calibration. But if it is really known what the problem is and in which magnitude

    Nowadays it is not so hard to check did BC change. Labradar (track to 100yd) can do that if change is big, although calculated BC is not usable. I am using this to check effectivness of pointing as smallest meplat is not always a good choice, nor highest BC (peak) in a respect of BC SD (labradar cannot check this).

    Bit more advanced can even use tools like McCoy Mc Drag and adapt drag coefficients if they have reliable and repetable range results, which is far away from easy and quick, that is true. But it can be done in a Mach range bullet is used. Just to have a good firing solution in a used range, not the fully correct drag curve.

    What I want say is. Although calibrating only MV in supersonic flight is a best way to go. There are exceptions. Sometimes it is necessary to inform the calculatir that different bullet is used.

  • Jonathan Bowman says:

    One crucial and not mentioned input variable is sight height over bore. Geometrically, if you “eyeball” that measurement you are introducing unnecessary error into your ballistic calculator.
    Thanks for the video guys, really enjoyed it.

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