How do you account for wind in Exbal or other software

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by ss7mm, Mar 25, 2008.

1. ss7mmWriters Guild

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I know most of you have run so many numbers that this is probably old stuff but it came up recently when I had a conversation with somebody about wind entry values in Exbal.

The guy I was talking to said he always set his Exbal at 1 mph for wind and then if the wind was blowing 5 mph he multiplied by 5 and if it was blowing 10 mph he multiplied by 10 (moved the decimal one point) and so on and so on.

I set mine at 10 mph and do the division or multiplication accordingly for whatever I read the wind at. I did the numbers in Exbal to show him. Everything was exactly the same except one had 1 mph input and the other had 10 mph input for the data.

You can see that if you used 1 mph it says .25 moa from 450 yards out to 1000 yards. Actually it says .25 moa out to 1150 yards. A 10 mph wind would mean, by multiplying by 10, that from 450 yards to 1150 yards you would hold or dial in 2.5 moa.

On the side that has the 10 mph used, you can see that at 450 yards it's 1.25 moa for windage and at 1000 yards it's 3.25 moa for windage and at 1150 yards it's 3.75 moa for windage.

That may not sound like much to some but if you're going to do it then you should be as precise as you can shouldn't you?

How do you guys set up your Exbal or other software for wind?

Last edited: Mar 25, 2008
2. VarmintWell-Known Member

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Dick I do what you do I use 10 mph and cut it down to what ever it is and go from there, Tim

3. MikecrWell-Known Member

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The guy's FOS

4. WildcatBWell-Known Member

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I don't think he is...

Exbal seems to be rounding to a click tolarance (1/4 click per moa)

I ran some numbers in JBL. If you run a 1 mph wind @1000 yards you get a windage of .1 moa (8.3 inches) . With a 10 mph wind you get windage of 7.9 moa ( 82.9 inches).

This guy's method seems to hold. The small differences here I'm sure are caused by rounding. The .1 moa is probably .79 rounding to the 1/10th of a moa.

I used the default bullet/velocity/caliber/elevation/temp/humidity for jbl.

I don't have exbal but maybe there's a way to set tolerance preferences? So instead of rounding to clicks you have it give you decimal moa's?

5. MikecrWell-Known Member

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Ok, I believe you.

6. ss7mmWriters Guild

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It does go to the nearest "click". In this case it's set to moa with 1/4 moa clicks.

It's just that the precision is better using 10 mph than by using 1 mph. At 1 mph it takes a long time before it goes from .25 to .5 because of the rounding, but with 10 mph you can see that, even with the rounding, it goes in finer and more accurate increments.

If you multiplied the .25 moa at 1000 yards by 10 to make it 10 mph then you come up with 2.5 moa.

If you compare that to the 10 mph figure of 3.25 moa you can see there is a difference of .75 moa at 1000 yards or 7.85"

If you look at the trajectory values you can see that in both cases it knows the wind drift and both charts agree on the value. It's just that there is a difference is what you would dial if you used the 1 mph factor instead of the 10 mph factor.

At 1150 yards, using the 1 mph factor, you would go from dialing 2.5 moa to dialing 5.0 moa while by using 10 mph factors you would already be dialing the right wind of 3.75". The 1 mph factor just limits its accuracy because of the rounding and this hurts you the farther out you go.

7. WildcatBWell-Known Member

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The problem is with exbal and not the method. With exbal - little wind: greater the error. Big wind: less error. If exbal doesn't let you change the accuracy... just come up with your 1 mph correction by plugging in a 10 mph wind and divide by 10... or better yet (if exbal will let you do it) plug in a 100 mph wind and divide by 100 (to minimize the error.) Use this result for your 1 mph reference.

I kind of like his idea. Once you have an accurate 1 mph correction, the math is very easy.

8. ss7mmWriters Guild

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That's right on. Theoretically I'd say the 1 mph method would be easier to do quickly in your head but, unfortunately, Exbal doesn't cooperate.

I already thought about the 100 mph thing but Exbal limits you to 60 mph. I guess they figure we won't be shooting if the wind gets over 60 mph.

I think I'd personally like to use the 1 mph method for the ease of doing it in my head quickly but I can't stand the inaccuracy of it so it looks like it's 10 mph and some quick math.

9. WildcatBWell-Known Member

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Do 60 then divide the answer by 60. Then compare that to JBM's with the same inputs. Maybe 60 will be accurate enough?

Anyway... I'm going to give this 1 mph method a try gun)

10. ss7mmWriters Guild

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I compared the results in Exbal using 10 mph and also 60 mph. They were very close, usually within 1/4 moa and 1/2 moa at the most. I don't know how the formulas work that they use and whether the software treats an increase in wind in a linear fashion from 1-60 mph or if there is some difference as the wind gets way higher. I think I'll just stick with the 10 mph factor. It's worked for a long time.

11. sscoyoteWell-Known Member

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Man, i can't rememver the guy's name right now, but he runs the practical riflery forum--same guy that came up with the Ladder system for reloading. Quite the educated LR shooter actually--Highpower i think. He also uses 1 mph dope instead of 10. I haven't tried it yet with my reticles, but intend to soon. I'm not sure how well it will work with reticles, since i divide the wind by the subtension. It oughtta be easier tho.

12. Ridge RunnerWell-Known Member

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SS, hunting here in wv it seems you have 3 different conditions, either no wind, 3-7 mph, or wind gusts from 8-20 mph. real windy days I don't hunt LR much, about 12 mph is my limit, so I set exbal at 3 mph and work from there seems like about evey shot I took last year I dialed in 2 MOA left wind.
RR