wind drift

Discussion in 'General Discussion' started by pressman, May 19, 2009.

  1. pressman

    pressman Well-Known Member

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    I have a long rangeshooting game that is actually pretty darn fun. you have to dope your wind and use your scope to calculate the distance and also use drop charts. it also teaches you all the calculation for mildot ranging and dope setting.
    but one thing they teach you is that if you have wind close to you NOT THE TARGET
    the wind has greater effect on the bullet.
    IS this correct cause i though i read some where that the wind closes to the target has the most effect because of the loss of speed. I know i have sure missed a few target on this game because i looked at the wind at the target not at my position.
    Please give me some pointers because playing this game is one thing to keep you sharp with calculation but in real life i do not want to miss because i did not know.

    Thanks guys
     
  2. tx hunter

    tx hunter Active Member

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    Not for sure about your question as I am just getting started in all this(rifle almost done). But I am curious about the game you mentioned. What is the name and where can I get it.
     

  3. pressman

    pressman Well-Known Member

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    it is called long range shooting, A friend of mine got it for me since i drive him crazy when he is with me. i will ask him where he got it. i play it on the computer so maybe if you google it you might find it.
    it really is a fun game and i even use exball with it and if i read the wind right exball is right on the money in the 6" square part of the target.
     
  4. jerrschmitt

    jerrschmitt Well-Known Member

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    Try www.shooterready.com. Not sure what game the OP has but it sounds the same as this one.

    Wind closest to you has the greatest effect. The reason is that if the wind at your muzzle blows your bullet left by 1 inch at one hundred yards it will be 10 inches off at 1000. If the wind at 1000 yards blows your bullet off 1 inch you'll still be off 1 inch at 1000. That is simplified and assumes no other wind which never happens but it explains the difference.
     
  5. eshell

    eshell Well-Known Member

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    Shooting extremely long ranges creates much more challenge, because while the wind is typically homogeneous when shooting short range, it can be from several different directions over the course of the bullet's flight if distances are long enough.

    As posted by jerrschmitt, wind "at the muzzle" (which is really wind "during the first portion of flight") has the greatest angular dispersion effect and is usually considered to be the most influential.

    Wind downrange also has substantial effect, due to the duration of exposure during the mid-range portion of flight, and also due to the reduced bullet velocity during the final portion of flight.

    Most long range target shooters will want to know what the mid-range wind is doing, as well as what the wind is doing at the firing point.

    Whenever possible, I will consider wind at the firing point, mid-range wind, and wind near the target. I think of it as wind during the first 25% of flight, the next 50% of flight, and the final 25% of flight, vs wind "at" the muzzle, wind "at" mid range" and wind "at" the target.

    If we have no wind data downrange, we only have part of the story, and it pays to learn the indicators that allow us to judge downrange wind speeds.
     
  6. ajhardle

    ajhardle Well-Known Member

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    1. wind at the muzzle is important because it affects the entire trajectory.
    2. wind downrange is important because the bullets travels slower.
    3. wind at midrange is important because the bullet is higher above the ground and probably has a higher wind speed than lower parts of the trajectory.
    4. more importantly for long range ( or really long range) is the transonic barrier. The coefficient of drag has a dramatic spike for long range bullets as they approach the sound barrier and wind drift is increased.
    5. or in certain cases the landscape will have variables that can have the greatest effect and be incredibly difficult to predict.
    So what you have to do is find an indicator and see what happens when you shoot, and shoot some more. If it is unpredictable, find a new indicator. Keep doing this for years and no-one will ever predict it perfectly, but we try and that's the fun of long range shooting.
     
  7. blipelt

    blipelt Well-Known Member

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    Plug the numbers into you ballistic calculator and you can see what the wind will do at a decreased velocity close to your target. Your chart will show you the velocity downrange at least mine do. I pay attention to down range wind but my biggest concern is the beginning of my bullet flight. But I am a flatlander, I can see how shooting in hilly or mountains would be different.

    Brent
     
  8. blipelt

    blipelt Well-Known Member

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    A little different question:

    I have a mentor who is a 11 time World Record holder and is in both Hall of Fames for benchrest and he has done this in less than ten years. To say the least he is a credible source. He explained to me about five years ago how spinning a lighter bullet harder actually decreases wind drift and increases energy. I haven't read anything anywhere about this since. Anyone have any experience?

    To clarify decreasing wind drift say you use a 6mm 58gr. vmax in a 14 twist and then a 8twist the 8 will have less wind drift and have more energy when dispatching p dogs for example.

    Brent