Let's all stop doing it wrong! (Wind Call Verbage)

Discussion in 'Long Range Hunting & Shooting' started by tresmon, Mar 18, 2011.

  1. tresmon

    tresmon Well-Known Member

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    What I'm going to attempt to contribute to LR shooting is to correct our language.

    All of us use the name of a wind from 45* or 1:30clock as "half value" when most of us know the sine to get our needed correction is .707.

    Imagine the confusion that gives new shooters. Imagine the confusion elementary school kids would have when a teacher asked what is 1/2 + 1/2? -expecting an answer of 1.414!

    I learned early on we CALLED it a "half value wind" but actually HAD TO multiply our FV wind data by ~.707~ to get our corection for """"""Half Value"""""".

    I don't know where the very first shooting instructor that started teaching us this screwball way got their schoolin, but where I went to grammer school 1/2 is .5 and .5 is 1/2.

    Imagine telling a class full of grade school kids who was about to learn fractions for the first time "Class for todays lesson, when I SAY 1/2 you just are supposed to know I REALLY MEAN 3/4. So I better not hear anyone saying 1/2 + 1/2 is 1. Nope the correct answer is 1 & 1/2."

    What??? But yet that's what we do & insinuate to new shooters.

    Here's an example of a pretty typical wind ref. sheet out of a data book:

    [​IMG]

    So you see on the wind clock that a wind at 45deg. / 1:30clock is called "HALF value." So that sounds really simple & is self explanatory- a real no brainer!

    Take our full value wind data for this shot and half it for this 45deg wind. That's simple, quick and easy and TOTALLY WRONG.

    We actually take the FV wind data, and multiply it by EXACTLY .707 to get the data for this shot. [.707 is very close to .75 or 3/4, hence my proposed new wind call name below]

    So we see that we call this wind one thing, but do the math with another thing and there goes simplicity and K.I.S.S. principles right out the window. Not to mention it needlessly complicates things for the new comer.

    Here's what I propose as the new standard in the educational industry for shooting:

    A. For the rookie to novice LR shooter:

    Wind direction (Degree/clock), Term, Sine
    0*, 12clock "No Value" N/A
    45*, 1:30clock "3Quarter Val." .707
    90*, 3clock "Full Val." N/A


    B. For the advanced shooter that can grade wind direction with more precision:

    Wind direction (Degree/clock), Term, Sine
    0*, 12 clock "No Value" N/A
    30*, 1 clock "Half Val." .5
    45*, 1:30clock "3/4 Val." .707
    60*, 2 clock "7/8 val." .866
    90*, 3 clock "Full value" N/A

    This way the wind name communicates the required sine and their is no confusion.

    If we split hairs no "3/4 value is not EXACTLY .707" and the same for "7/8 Value" these decimal places ares so close that if the shooter can't remember the exact sine, he can multiply full wind data by the direction of the call/term of the wind and it introduce no error noticeable on target as the difference of these decimal places are minuscule on target.

    I seriously suggest every LR educational institution take on this new terminology ASAP.

    Mod's can we make this a sticky to get the word out??
     
  2. Kevin Cram

    Kevin Cram <b>SPONSOR</b>

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    WOW !!!

    I've been long range hunting for over 20 years and have killed, been part of or helped in taking at least 1000 game animals from woodchucks to bear just here in PA from 300 yards to over 2000 yards. I've never been more confused. I understand wind and how it effects my bullet in theory. I also understand the coriolis effect and spin drift. At least where I hunt we shoot from the tops of mountains across valleys sometimes several valleys and ridges. Usually where we shoot from we are some what protected from the main wind stream by trees or land contour. If I have a 3-5 mph wind from 9-3 where I sit but 400 yards out I'm shooting across the middle of a valley with no trees to block any wind maybe a 7-10 mph wind from 10-4 plus a steep hillside creating a lift or drop then across a ridge and across another valley there is no way to measure the wind. Experience and practice shooting from these types of locations is what makes hits. To know the theory is one thing, but most of the time real world situations are another. I applaud your effort and math but I think you'll confuse more than you'll help.
     

  3. mike33

    mike33 Well-Known Member

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    Well said Kevin. :D I know i have a language problem on a missed shot.
    mike
     
  4. tresmon

    tresmon Well-Known Member

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    I get what your saying but it appears you missed what I was saying.

    What I wrote has nothing to do with up/down drafts.

    It's a accurate means to figure a decent correction for a crosswind at an odd or oblique angle wether your shooting 200 yards or 1200.

    What would you have a guy do that perhaps does not the experience you may? Just kind point it "oh about there" at the skyline and pull the trigger? No the less experienced need some solid means of working out the problem.

    This I have given him.

    I never presented it or inferred it to be a voodoo magical solution for 6 different varying wind bands of 6 different magnitudes at 6 different ranges between the muzzle and target.

    Evening fellas.
    T
     
  5. Akiona

    Akiona Well-Known Member

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    I usually call the wind "stupid", with a few other words.:D
     
  6. SBruce

    SBruce Well-Known Member

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    Tres,

    For what it's worth, I agree, and further more appreciate your attempts.

    I don't have the mountain/canyon/ridge and valley shooting experience that KC mentions, but I do have alot of flat land experience shooting in the wind, and when shooting small targets in the wind, it's a huge benefit to take all winds into consideration. The "true" head or tail wind hardly ever exists.

    Tons of prarie dogs with small caliber low bc bullets taught me that even a 15 degree wind (or 12:30/11:30/5:30/6:30) has a drift value. Ballistic programs give it roughly 25% or 1/4 value.

    Folks that don't have a field ballistic program can use a basic small scientific calculator to figure drift and angle corrections, using the numbers you provided. I've done it, I didn't have a ballistic program until recently.

    Thanks again.:)
     
  7. blipelt

    blipelt Well-Known Member

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    interesting read, my question is if it is totally wrong, will it cause you to miss a 1/2moa target at the distance? What is the error?
     
    Last edited: Mar 19, 2011
  8. rscott5028

    rscott5028 Well-Known Member

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    I see your point and I hate that it's messed up. But, 2 wrongs don't make a right.

    You a correct in that 1/2 does not equal .707.

    But, neither does 3/4 for that matter.

    And seriously, .707? Who carries it out to 3 decimal places? For that to be meaningful, you need a lot more pie slices.

    And, what do you do with all those cross winds that seem to contradict and confound eachother like Kevin explained?
     
  9. SBruce

    SBruce Well-Known Member

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    Let's take the example of a 45 degree wind. The ballistic programs will give you a drift value of .71 or 71% of what a 90 degree true crosswind gives. There is also a vertical displacement, but that's another story. So we'll just use this example for now.

    My new coyote rifle should drift 20" at 600 yds with a true 90 degree crosswind at 10 mph (not at all unrealistic in Wyoming). Let's say that the wind is blowing from 1:30 or 45 degrees right of dead ahead and I use the old "1/2 value" adjustment. That means I hold or dial 10 inches for wind. When the true displacement is actually 14.2", over 4" more drift than I've figured.

    This said coyote is sitting on his butt barking at me and wont come any closer. His chest cavity is only about 8" wide counting the fur. I hold dead center (leaves 4" each side to play with) and miss!! Worse yet, just nick him and burn his skin on the left side, now he's a very educated coyote!! Next time, he'll just turn and high tail it out of the country when he hears a call.

    This example is not a 1/2 minute target, but a larger than 1 minute target. If it were a prarie dog (a 1/2 minute target) it would be a clean miss, and a miss by nearly a full praire dog width.
     
    Last edited: Mar 19, 2011
  10. KRP

    KRP Well-Known Member

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    IPHY and MOA are interchangeable because they are "close enough" right? Your .707=.75 is going to result in a similar compounding error. I agree about the flaws with the posted wind chart and appreciate you pointing that out to those that don't know though. Instead of dumbing things down why don't we expect people to be capable of grade school math?
     
  11. loosesniper2000

    loosesniper2000 Well-Known Member

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    It used to be called a "swag" and now with all the high tech equipment it's an educated "swag"
    I've messed around with long distance shooting about as much as anybody on here and I agree with Kevins post that you meet all conditions which are inconsistent. I've never shot in perfect conditions and the fact that all the ascribed methods are out there mean one thing...it's still a guess. You're whole theory can be blown of when you meet a headwind 100yds out after shooting in a 5mph crosswind. Point being is even if it works out on paper it's still up to the discretion of the shooter.
    I'll be shooting this afternoon with mike33 on here and we'll be going out to 1300yds. In the valley I shoot in, nothing remains the same. Yeah I have the kestrol 3500 and Exball on my handheld pc and I still miss even when everything is entered perfectly!
    I'll give you a quick example, years ago I had my 75lb 300Weath at the IBS 1000yd shoot in Quantico Va
    I had 9 shots in about 5-6 inches and the clouds covered the sun on my 10th shot. Guess what, the bullet dropped 6 inches. Point being, even with all the math computed the sun/bp/temp plays just as big a role. So...it's still a swag
     
  12. blipelt

    blipelt Well-Known Member

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    Thanks Sbruce for info. I updated my computer and haven't found any software I like. A friend is working on some software for me. From what I have played with so far it is going to be worth the wait. I was curious when the error was going to start to matter. What cal. is your coyote rifle?

    I tend to disagree with the language totally wrong. At a certain distance/size of target the error will start to play a roll. But I tend to believe wind doping is more of an instinct than a equation. The more math/science you take the more you understand it is an educated guess!


    Brent
     
  13. SBruce

    SBruce Well-Known Member

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    Yes, the ballistic software is a great place to learn the mathmatics side of LR shooting. When I was trying to figure it all out, we didn't have the ballistic programs. I had to read the Sierra Book and VHA articles and trial/error those long equations till I got it right. Contrary to what some believe, there is some math involved, and the longer the shot/smaller the target, the more important the numbers are. The math/ballistics science takes it from a Wild Ass Guess to an Educated Guess.

    I am not saying that ballistic programs and math/trig make anyone a better shot..............IMO, practice, attention to detail, determination/discipline and understanding the wind and other elements are also some of the things that will make or break the deal. Alot of ammo downrange is key. When I was spotting for a friend last fall, I found myself going off of instinct (educated guess) rather that what the program said when it came to drifts/wind calls, because I could tell that the wind wasn't steady all the way to the target, or that we weren't measuring the full force from our sheltered position.

    My new coyote rifle is a 6 Long Dasher. It's a necked down 6.5X47 Lapua with a longer body and sharper 40 degree shoulder. It's about a 5% increase in capacity over the 6.5X47 Lapua case, but it's 6mm. The 20" at 600 yds is based on the 105 A-Max going 3110'/sec. I've gotten 3300'/sec with same bullet, but that was a little warm for my liking. It was still 1.5 grns under absolute maximum, but warm nonetheless. Even at 3100'/sec, this cartidge is doing the same thing that David Tubbs 6XC is doing (according to his load data on it). He shoots that round in 1000 yd competition.

    My old favorite was a 220 Swift and then more recently a 22-250. Both of these are blown off at least twice the amount that the 6LD is (with normal bullets weights). We didn't have the ultra heavy high bc 22's either when I did alot of my prarie dog shooting. Wind drift made me a very humble fellow in those days.

    The example I gave would apply at a much closer range with the 22-250. To put that same example in perspective, the big 338 Edge with a 300 SMK at 2800'/sec. supposedly has 20" of drift at 725 yds. In my experience with same load, it didn't drift quite as much as the program said, but that was limited experience, and we weren't figuring any Spin Drift or Coriolis effects in.

    Anyway, no matter what the cartridge is, at some point the details (or lack of) will start to add up and cause a miss. Not even to mention the fact that as we get further out, the bullets POI will just naturally be further from our POA to begin with. Not taking into account all the variables possible and not taking the time to do the math correctly just adds injury to insult.

    Tres is just trying to show that using .5 instead of .7 will result in a miss. All other factors being equal, that is the absolute truth. If we're going to "shortcut" it, then using 3/4 is certainly closer than using 1/2.:)
     
    Last edited: Mar 19, 2011
  14. blipelt

    blipelt Well-Known Member

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    SBruce, I understand what is being said, maybe a little to well. My brother codes/designs ballistics programs. Oh and a couple years of Calculus and physics helps. What I am getting at is the errors are always present(not as large as .5 to .707). Sig. figs. just an example. You put it best, the equation is the starting point. The smaller and farther you go the more attention to detail you need. I am not disagreeing I just miss the good discussions that seem to be lacking these days.


    Brent
     
    Last edited: Mar 19, 2011