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Mar 25th, 2012
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"Calculating" your wind calls- for long range shooting #7142209
04/16/18 03:34 PM
04/16/18 03:34 PM
Joined: Sep 2009
Posts: 13,969
Lewisville, TX
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ChadTRG42 Online happy OP
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ChadTRG42  Online Happy OP
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Joined: Sep 2009
Posts: 13,969
Lewisville, TX
In the last 2 days, I have been asked about how I make my wind calls. I figured I would pass this info on. Shooters sometimes look at me puzzled when I tell them I would rather shoot in a full value wind than a head or tail wind, or a wind that is variable from the front or rear. Why? Because I can "calculate" the full value wind much better than I can predict the changes in wind from the front or rear. So, here's how I do it.

Take the ol' trusty 6.5 Creemoor that everyone has now. We are shooting a 140 grain ELD-M at 2750 fps with a G7 BC of .326. Below is a drop chart and wind value of this bullet in mils. (For moa, you do the exact same thing, just use moa) I run all my wind charts in 1 mph increments to be more precise, and keep the math easier and simple. I analyze the shooting range and calculate my wind at 8 mph coming from my 2 o'clock position. My target is 500 yards away. Looking at the drop chart, I see my 1 mph wind value is .08 mils. So, .08 times 8 mph is .64 mils for a full value 3 o'clock or 9 o'clock wind. My wind is coming from the 2 o'clock, so I take 87% value of the .64 mils, which would be .55 mils (.64 times .87). Now, .55 is half way between .5 and .6, so I would hold .5 mil and make any slight adjustment on my second shot, if needed. But either way, I'm going to be near dead on for my wind call.
(My fast math method- .08 x 8mph = .64; 10% of .64 is .06; .06 minus .64 is .57 mils)

Let's do another one. Target is 700 yards away in a 14 mph wind coming from the 7:30 position. 1 mph wind drift is .12 mils. .12 times 14 mph is 1.68 mils (this is a full value wind). Wind out of the 7:30 position takes 70% of the full value wind, so 1.68 times .70 is 1.17. I would round up and hold 1.2 mils into the wind.
(My fast math method- .10 x 14mph = 1.4, plus .02 x 14 mph = .28 (round up to .3), for 1.7 mils full value. 30% off is about 1.2 mils)

This is the exact system I use for my wind calculations. Once I learned the "clock" system, I went from guessing my wind to actually "calculating" my wind. My first round impacts became much more common. The fast math method is how my brain often works in computing the wind quickly in my head. Often times my quick calculations are easily within less than .1 of the actual calculated wind. I break down the figures in tenths most of the time in my head and can calculate it quickly. But that's just me. You may think or do math differently to get to the same amount, but do what works for you!

What's easy about it is, you really only need to remember 3 values-
.5 or half value at 1 o'clock
.7 or 71% value at 1:30
.87 or 87% at 2:30

From there, it's the same all the way around the clock system, depending on which angle the wind is coming from. This is how I calculate my wind. It's simple and fast to run. And yes, I often have a calculator on me if I feel like I need to compute it. Often times I'll round up the .87 to .9, and calculate a 10% less in my head, and run that if the wind isn't blowing much. It will certainly get you close enough on target to make a hit.


Range Elev Wind
(yards) (mil) (mil)
0 --- 1 mph
100 0 0.01
200 -0.44 0.03
300 -1.12 0.05
400 -1.91 0.06
500 -2.78 0.08
600 -3.74 0.1
700 -4.79 0.12
800 -5.93 0.14



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Re: "Calculating" your wind calls- for long range shooting [Re: ChadTRG42] #7142260
04/16/18 04:21 PM
04/16/18 04:21 PM
Joined: Dec 2008
Posts: 26,890
Wolfe City, TX
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FiremanJG Online content
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FiremanJG  Online Content
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Wolfe City, TX
I go a different route.

5 mph at 3 or 9 o'clock is what I start with.

200 yards .1
300 .2
400 .3
500 .4
600 .5
700 .6
800 .7
900 .8
1000 .9

10 mph, double those holds. 15 mph, triple those holds, 20 mph quadruple those holds. 2.5 mph, cut the original 5 mph holds in half.

1-2 o'clock, 4-5 o'clock, 7-8 o'clock, 10-11 o'clock, cut those holds in half.

Multiply and divide as needed.

Keeping the numbers in my head will tell me what it is doing either with a hit, or a miss. So, at 500 yards if a 1.0 Mil hold worked, that's telling me the wind needs a 12 mph hold. Jump straight to 800 yards, 12 mph is what I learned

.7 per 5 mph is .7 X 2.5= 2.0 Mils

The trick is judging what it is doing based on what you see. Grass, brush, trees, mirage. My eyes are my wind meter. At The Lone Survivor Benefit Match last weekend, guys were walking around with their Kestrels. One asked me how do I deal with this wind since those fellas were from Louisiana and did not have this much wind to deal with. So off we went with me writing down the data above. They loved it. They did very well all weekend. They also said "we almost never have to leave steel in the reticle". Meaning their wind favor will still have the vertical stata on the steel. When the wind is 10-20 that is not going to fly. Saturday it was 10-20, but a 3 o'clock cross wind. Sunday morning it had all died, and I said "this sucks". "Garvey yoy outta your mind if you want that wind we had yesterday!" I said, watch, we will have a fish tailing wind, no mirage and you'll miss but not know which side. About 4 hours later, they were in complete agreement. The stage dee was R.O-ing told the tale. We shot the same loaction in high wind, on Saturday, and I got more hits. Next day, the wind was low but squirrelly, less hits.



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Re: "Calculating" your wind calls- for long range shooting [Re: ChadTRG42] #7142662
04/17/18 12:18 AM
04/17/18 12:18 AM
Joined: Feb 2009
Posts: 101
Roanoke, TX
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TORNracer Offline
Woodsman
TORNracer  Offline
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Joined: Feb 2009
Posts: 101
Roanoke, TX
Both awesome posts, thanks for sharing! I told a friend the other day -“gravity is easy, wind is haaaaard!”

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