Range Report Wind estimation fomula

[callen3615]

I was reading a army sniper manual the other day and read about a formula that let you calculate and correct for wind. Im new to long range shooting, (if it isnt obvious by now). This was the formula:

(R divided by 100 times V) divided by 20

R= range in meters
V= velocity of wind
20= the constant for the m118 round.

It also stated that if you weren't shooting the m118 round the constant would be different. The m118 is a 175gr ball round. I shoot 147 gr boat tails out of my 308. How do I figure out what the constant is for my 147gr bullets?

 

[SPRINKLE]

Re: Wind estimation fomula

Range in 100 yards, X speed in mph
_________________________________________= MOA windage

15

out to 500 yards
600 divide by 14
700 divide by 13
800 divide by 13
900 divide by 12
1000 divide by 11
this works pretty good

 

[Lindy]

Re: Wind estimation fomula

You might just as well calculate the constants for your particular load.

Set up a ballistic program for your load. Set the wind speed for some value, say, 10 mph.

Run the calculation, and look at the wind values. Then use this formula for each distance you want a constant for:

<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
(range in yards/100) * wind (mph)
constant = ----------------------------------
wind hold(mils)
</pre></div></div>

For example, suppose at 700 yards, the program says the wind hold is 1.7 mils for a 10-mph wind.

Then, using the formula above,

Constant = (700 /100) * 10 / 1.7

or

Constant = 7 * 10 / 1.7 = 41.

Do that for each distance. You will likely find that inside 500 or 600 yards, depending on the load, you can use the same constant.

 

[zenbiker]

Re: Wind estimation fomula

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: tsprink</div><div class="ubbcode-body">Its time for America to Repent for her sins... </div></div>

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lindy</div><div class="ubbcode-body">what lindy said </div></div>

+1, except I take the 10mph full value drift at a given yardage and divide that by 10 to get drift value per mph of wind. Multiply by wind speed to get drift, correcting by rosette for clock vector. Homework ahead of time keeps field calculations simple.