Wind Formula for .308 and range estimation Mil

everypenny

Hi guys,


Don't know if you have seen this before but hopefully it'll be of help.


Its a simple method of aiming off for wind for .308 cal ammo using the formula:
(Distance in meters/1000) x (wind speed/4) = Mil hold in direction of wind.

For distances of 700 meters +, add .1 mil so the formula would read
[(Distance in meters/1000) +.1] x (wind speed/4) = Mil hold in direction of wind.
This is due to the round slowing down after 700 meters to the point that the wind would have another .1 mil of an effect on it per 100 meters.


The BC of an average .308 round is .4 hence the wind being divided by 4. If your BC is closer to .3 then divide by 3 etc.
Ranges are rounded off to the nearest 100.


So a .308 being fired at 500m in a 12 mph wind would be:
(Distance in meters/1000) x (wind speed/4) = Mil hold in direction of wind
(500/1000) x (12/4)
.5 x 3 = 1.5 mil hold.


777 m at 8 mph =
[(800/1000) +.1] x (8/4)
(.8+.1) x 2
.9x2 0 1.8 mill hold.


Info on ranging with Mill is also here.


Cheers,


EP

Jonty

So how do you cope with an oblique wind direction, just halve the wind speed value?

everypenny

Use a wind clock.

Quick google search will find a good one. Here's one I found.

http://i222.photobucket.com/albums/dd220/Meadowmucker/Misc/WindDirectionClock.jpg


It basically gives you the % of your wind call. So if your wind hold is 1.6m and the wind is coming at you from your 8 o' clock then you use 86% of the wind.
That's 7/8ths in old money so you divide 1.6 by 8 and multiply by seven to get 1.4.

There are probably more accurate methods out there. If anyone knows one then will ye let me know?

bravestar

everypenny wrote: »

There are probably more accurate methods out there. If anyone knows one then will ye let me know?

Iphone + Ballistic AE(advanced wind feature) =

everypenny

For $20 it would want to be good!


I prefer iStrelok. (http://istrelok.borisov.mobi/) its on the iPhone and on Android. Never had a problem with it. As good as if not better then all the ballistic calculators I've ever used and the number of reticles it supports is phenomenal.


It does every thing from air rifles to .5! I'm waiting for the indirect fire version

dogcityroller

Have to agree with strelok. I've used ballistic ,isnipe and a few of the others, but I always go back to strelok because the wind setting on it is far and away the easiest to use. I live in the north and reload my own bullets. I've tuned strelok along with my bullets to achieve first round hits on rabbits and crows out to 740 yards with my blaser lrs2 in 223. I cannot recommend it enough.