Range Report wind call "rehab"

[obilly]

I'm a former shooter trained to use range constants to calculate for wind. Problem is I'm no longer shooting a 168g sierra bthp @ 2770 fps, so all those range constants I have committed to memory are junk, I would like to figure out how to calculate new constants for different rounds at different velocities. So far all I have been able to find is programs that do all the work for me. Problem is.. I feel like I'm being spoon-fed and I would at least like to know how it works before I use it. I don’t care about complicated math “I’ve got nothing better to do”. Also trial and error is cost prohibitive. Anyone know how to help?

 

[goober]

Re: wind call "rehab"

some stuff i cut and pasted-sterlingshooter wrote the first part and cant remember who did the rest

I use a simple formula (range divided by 100 times half or full value wind in MPH divided by constant of 10). This yields an answer in MOA of drift. I can thereafter click or favor for a good hit. When favoring with irons, where converting MOA to inches may be useful, I can also easily convert to inches without need for a calculator. Of course, whether you need a fomula which gives you an answer in MOA or mils will be determined by what sort of sight you've got. One more thing, the constant of 10 is not exact science; but, for mid-range to LR, for most any standard high velocity bullet, it gets the job done. As far as how good I am, I expect good first round hits for myself as well as students.


(Range[hundreds] X wind velocity MPH) / Constant = Adjustment in MOA

Constants:
100-500m =15
600m =14
700-800m =13
900m =12
1000m =11







Environmental indicators can be grass, trees, flags, smoke, and my favorite for under ~8mph; mirage.

I use what was taught to me as the "British method." A reference of wind adjustments in mils for 10mph FV winds at 50 meter increments. Yes, I go by meters, so sue me.

Target at 500m= reference dictates 2.0mil adjustment at 10mph FV
Actual wind is 5 mph, half value

2.0mil x 0.5(actual wind speed) x 0.5 (wind value) = 0.5 mil hold

I shoot .308 175gr SMK, normally I hold for wind, but occasionally dial. The reference is derived from a ballistic calculator. This method has worked well for me thus far.

 

[azimutha]

Re: wind call "rehab"

I just find it easiest to memorize 8 wind values in mils in increments from 300-1000 yards for 10 mph. Wind effect being linear, e.g. a 20 mph wind doubles each value, it works fairly well. Granted this only works for one particular load, but I'm not sure how you're going to find some simple formula that applies to a variety of loads.

Because I handload and hate adjusting dies back and forth anyway, I have streamlined everything I can. I've got one very good rifle now and two loads - one for target/long-range and the other for hunting. They are close enough that there is little difference out to 500.

 

[timelinex]

Re: wind call "rehab"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: azimutha</div><div class="ubbcode-body"> Wind effect being linear, e.g. a 20 mph wind doubles each value, </div></div>
The biggest problem with it is wind effect is NOT linear

 

[Proarc]

Re: wind call "rehab"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ch'e</div><div class="ubbcode-body">some stuff i cut and pasted-sterlingshooter wrote the first part and cant remember who did the rest

I use a simple formula (range divided by 100 times half or full value wind in MPH divided by constant of 10). This yields an answer in MOA of drift. I can thereafter click or favor for a good hit. When favoring with irons, where converting MOA to inches may be useful, I can also easily convert to inches without need for a calculator. Of course, whether you need a fomula which gives you an answer in MOA or mils will be determined by what sort of sight you've got. One more thing, the constant of 10 is not exact science; but, for mid-range to LR, for most any standard high velocity bullet, it gets the job done. As far as how good I am, I expect good first round hits for myself as well as students.


(Range[hundreds] X wind velocity MPH) / Constant = Adjustment in MOA

Constants:
100-500m =15
600m =14
700-800m =13
900m =12
1000m =11







Environmental indicators can be grass, trees, flags, smoke, and my favorite for under ~8mph; mirage.

I use what was taught to me as the "British method." A reference of wind adjustments in mils for 10mph FV winds at 50 meter increments. Yes, I go by meters, so sue me.

Target at 500m= reference dictates 2.0mil adjustment at 10mph FV
Actual wind is 5 mph, half value

2.0mil x 0.5(actual wind speed) x 0.5 (wind value) = 0.5 mil hold

I shoot .308 175gr SMK, normally I hold for wind, but occasionally dial. The reference is derived from a ballistic calculator. This method has worked well for me thus far.
</div></div>

Do you have the constants for mil holds?

 

[goober]

Re: wind call "rehab"

No but maybe you could ask Sterlingshooter

 

[azimutha]

Re: wind call "rehab"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: timelinex</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: azimutha</div><div class="ubbcode-body"> Wind effect being linear, e.g. a 20 mph wind doubles each value, </div></div>
The biggest problem with it is wind effect is NOT linear </div></div>
Maybe my terminology is off, but enter values of 10, 20 and 40 MPH in JBM or another ballistics calculator and tell me how the value for any range is not twice the previous value.

 

[obilly]

Re: wind call "rehab"

Thanks for the prompt reply gents, just to clarify.. I am using the formula (range/100)x wind/”constant”=wind call
I guess what I'm asking is how do “they” figure out the # I'm using for my constant? If I know this I can adjust for a different BC or bullet slowdown ect. I'm hoping this will help fine tune LR accuracy ESPECIALLY with apposing wind calls, Which I could also use a little advice on.
I shoot in a canyon that has some screwy winds. I could go further upslope and get a more uniform wind call but why

. Anyway, anyone have some cool tricks with a wind call that looks like this..
1-300y L-to-r 10mph fv, 3-500y no wind, 5-1000y 5mph r-to-L fv. I'm getting on paper but I like the x ring.

 

[gstaylorg]

Re: wind call "rehab"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: azimutha</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: timelinex</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: azimutha</div><div class="ubbcode-body"> Wind effect being linear, e.g. a 20 mph wind doubles each value, </div></div>
The biggest problem with it is wind effect is NOT linear </div></div>
Maybe my terminology is off, but enter values of 10, 20 and 40 MPH in JBM or another ballistics calculator and tell me how the value for any range is not twice the previous value. </div></div>

I think what was meant is that it is not linear with respect to distance. In other words, a full value wind will deflect a projectile at 1000 yds more than double the the amount it deflects the same projectile at 500 yd.

 

[azimutha]

Re: wind call "rehab"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gstaylorg</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: azimutha</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: timelinex</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: azimutha</div><div class="ubbcode-body"> Wind effect being linear, e.g. a 20 mph wind doubles each value, </div></div>
The biggest problem with it is wind effect is NOT linear </div></div>
Maybe my terminology is off, but enter values of 10, 20 and 40 MPH in JBM or another ballistics calculator and tell me how the value for any range is not twice the previous value. </div></div>

I think what was meant is that it is not linear with respect to distance. In other words, a full value wind will deflect a projectile at 1000 yds more than double the the amount it deflects the same projectile at 500 yd. </div></div>I'm 100% in agreement on that and should have made my point more clearly in the first place. Again, at a given range, a 20 mph wind is going to deflect the bullet twice as much in a 10 MPH wind, e.g. @ 500 yards 38" vs. 19"

 

[jwoolf]

Re: wind call "rehab"

if you make a ballistic card with a 10mph full value wind, you can move the decimal place over for a 1mph wind and do the math in your head easily... anyway, that's how I do it.

I just figure out what the wind is blowing, and if, for example we're at 1000yds and a 10mph wind is going to move the bullet 5.0moa with a 10mph wind and I have th 13mph wind, I just say 5moa + (.5 * 3) = 6.5moa then hold over and shoot.

It may not work for everybody but, it's easy.

 

[doc76251]

Re: wind call "rehab"

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jwoolf</div><div class="ubbcode-body">if you make a ballistic card with a 10mph full value wind, you can move the decimal place over for a 1mph wind and do the math in your head easily... anyway, that's how I do it.

I just figure out what the wind is blowing, and if, for example we're at 1000yds and a 10mph wind is going to move the bullet 5.0moa with a 10mph wind and I have th 13mph wind, I just say 5moa + (.5 * 3) = 6.5moa then hold over and shoot.

It may not work for everybody but, it's easy. </div></div>

THIS^^^^

With as subjective as wind can be based on too many factors to list having a base that can be easily adapted to the situation is handy.

Then (Base Data * Experience) / (MIRAGE) = a pretty good hit

Cheers,

Doc

 

[dwt]

Re: wind call "rehab"

The worst trouble with wind is,it changes !