true bullet coefficient

Discussion in 'Long Range Hunting & Shooting' started by mo, Aug 9, 2009.

  1. mo

    mo Well-Known Member

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    I think I read somewhere that if you get muzzle velocity and then get your velocity from a 100 yd. you can get your true bullet coefficient. Is that correct? Does anyone know that formula?
     
  2. Topshot

    Topshot Well-Known Member

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    Not real practical. Too many errors on such a short distance.

    You have a very short time of flight and the accuracy of your chronograph to think about that may be a few%.

    If you are interested in such things, buy Bryan Litz book.
     

  3. britz

    britz Well-Known Member

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    You need to spread the two readings out over a longer distance. The farther apart the more accurate you will be in figuring your BC.

    Here is a link to Jbm calcuations page that will help you.

    http://www.jbmballistics.com/calculations/calculations.html
     
  4. jenr234

    jenr234 Member

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    Brian Litz's book is excellent,easy to understand and not too technical.
     
  5. mo

    mo Well-Known Member

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    thanks gentlemen.
     
  6. Michael Eichele

    Michael Eichele Well-Known Member

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    2 chronies work fine for a good place to start. The only thing you cant get is a drag model but will give you a DANG good place to start. 3 different times this year with 3 different loads I used the double chrony method to come up with a BC and put first round hits in the X ring at 700 yards.

    My chronies are 300 yards apart. As far as caluclations, it is best to use a ballistic calculator.
     
  7. MontanaRifleman

    MontanaRifleman Well-Known Member

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  8. mo

    mo Well-Known Member

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    I ordered his book today...