Which Wind to use?

Discussion in 'Long Range Hunting & Shooting' started by tracker12ga, Aug 10, 2009.

  1. tracker12ga

    tracker12ga Well-Known Member

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    I'm leraning about the wind through trial and error. I am getting a pretty good idea when it comes to constant winds from muzzle to target. However, I'm getting a little confused when wind speeds and/ or directions change one or more times down range. Which, at greater ranges, this seems to be the norm. So, which wind do I go by? At the muzzle, Mid range, or near the target? All three? LOL. Thanks for any help. :)
     
  2. nevada

    nevada Member

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    with the little experience i have, id say the wind at the muzzle is least important. as that is when the bullet is traveling the fastest, and least affected.

    midrange, and close to the target would have the most affect....


    i know on saturday, i was shooting, and it was VERY(20+) windy at the muzzle. very little wind on target. we did not have to compensate for the wind at all.
     

  3. bigbuck

    bigbuck Well-Known Member

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    I'm glad you asked this question. I thought that it wouldn't matter at the muzzle ,until I seen carlocks video and I noticed what I thought to be a wind flag or a piece of ribben about 4 feet from his gun . maybe it does matter at the muzzle maybe not.
     
  4. ss7mm

    ss7mm Writers Guild

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    Any movement of a bullet close to the muzzle as opposed to farther downrange, causes the bullet to be off line by a certain degree/angle. This angle is there permanently and unless you get a wind from a different direction way out there, the bullet will only be farther off line the farther the target is from the muzzle. It doesn't come back to the original line of sight, it only continues off on the angle caused originally and the farther out you get the more off line from the target you will be.
     
  5. tracker12ga

    tracker12ga Well-Known Member

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    Thanks for the replies so far.

    I was also under the assumption, that the bullet was traveing fast enough out of the muzzle that it wouldnt matter what the wind was doing there. Only when the bullet started to loose velocity would the wind start to effect it.

    SS7mm, has it been your experience that even moderate wind at the muzzle can push the bullet immediatly after leaving the pipe?
     
  6. ss7mm

    ss7mm Writers Guild

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    It's rare to only have wind "right at the muzzle". What I'm saying is that if you are shooting at say, 1000 yards and have a wind condition in the first 300-500 yards then it will effect the flight of the bullet from the muzzle to the target.

    If you only had wind "right at the muzzle" then the effect would be minimal as the velocity vs. the short distance of wind effecting the bullet would probably be something you could ignore.

    In canyon country of the west it's highly unusual to only have wind "right at the muzzle" so the point I'm making is that if you have wind effecting the bullet in the first part of a 1000 yard shot then the distance off line will be greater at 1000 yards than if you only had wind acting on the bullet in the last 200-300 yards.
     
  7. tracker12ga

    tracker12ga Well-Known Member

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    Alright, I think I just had a eureka moment hear. From what you guys are saying and from another archived post that I read, if you have a wind that pushes the bullet 1" at 100yds, then you will have a 10" drift at 1000yds. Compared to having the wind push at closer ranges to the target, the drift will be less.
     
  8. ss7mm

    ss7mm Writers Guild

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    Now you're getting it. The angle created by a wind in the first part of flight stays in effect all the way to the target. I'm making up a drawing of the effect and will get it up as soon as it's done.
     
  9. ss7mm

    ss7mm Writers Guild

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    In the picture below the angle of the flight of the bullet offline to the right is the same is all examples. You can see how the flight of the bullet is effected if the wind is in the first part of the flight and how it effected if the wind is only farther on out.

    [​IMG]
     
  10. tracker12ga

    tracker12ga Well-Known Member

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    Thanks. ill be waiting....
     
  11. nevada

    nevada Member

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    but it takes more wind at the muzzle to affect the flight of the bullet.
     
  12. JLR

    JLR Well-Known Member

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    Just keep in mind that the only thing you know for sure IS the wind at the muzzle. The rest is a good guess at best. I personally will try to work out some kind of average based on what I see throughout the whole range I'm shooting.

    I think any of us that shoot in canyon country can admit that there's been more times than a few that you make the best guess you can come up with and let one rip.......then go WOW, WTF happened there?

    So what does one do?........shoot in the worst conditions you can as much as you can. The more you shoot in crappy conditions, the better your guesses will get.gun)
     
  13. milanuk

    milanuk Well-Known Member

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    What ss7mm posted is an excellent text book explanation. In a perfect world, the 'near' wind usually tends to have more effect than the wind right at the target.

    Unfortunately we, or at least *I*, don't live in a perfect world. :D

    The terrain over which you're shooting has a lot to do with what matters - is there a cut in the trees further downrange, allowing a nice 'river' of wind to come through and smack your bullet about? Are there multiple ridges between you and the target that may give you some fits with vertical on target? Etc. and so on.

    The 'near' wind theory makes logical sense... if you take the time to work out the numbers for a regular trajectory out to say 1k yds and then use start playing with wind values at various distances, the near wind does have the most effect, despite the velocity decay further downrange. The fly in the ointment per se, is one that most of us don't normally think about all that much - how high the bullet is off the ground at any given point in the trajectory.

    Most of us have probably noticed that the wind often seems a lot stronger when we are standing straight up with our head 6'+ into the wind, vs. when we are laying down about a foot above ground. Now consider that your bullet is flying 10-12' over the line of sight, and god only knows how much over the terrain (depending on where you're shooting - even KD ranges aren't perfectly flat)... and the wind speed can pick up considerably as the bullet gets higher above ground. Even then it is rarely consistent.

    So in effect its probably not so much the 'near' wind, nor the 'far' wind, but more the 'mid' wind where the bullet is at the apogee of its trajectory.

    To be fair, this isn't something I came up with on my own. It's something I read in Bryan Litz's new book 'Applied Ballistics', and kind of smacked myself in the head as I read it, as it explains (to me) why when I get a firing point where I can actually use my spotting scope to watch the mirage, most long-range KD shooters focus back to about 2/3 the distance down range - which is awful close to the 'peak' of the trajectory.


    YMMV,

    Monte
     
  14. Bravo 4

    Bravo 4 Well-Known Member

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    You need to TRY to take into account how any/all winds can affect your bullet. SS7MM is correct in saying the earlier in a bullets flight the wind deflects it from its original path the greater the deflection will be at the intended target. Milanuk is correct in saying that the wind velocity is usually higher at the bullets maximum ordanance (highest point in trajectory) which is approximately 2/3 the distance to the target (according to ballisticians that work for the military).