# SHOOTERS : Doping Wind?



## skeeter (May 4, 2009)

I'm starting to look into long range shooting. I understand bullet drop, but I have a very small understanding of how wind effects bullets and how to compensate for it... can anyone explain this to me?


----------



## Diamondback 2/2 (May 5, 2009)

The best way to view the effects of wind is to think of your bullet as a football. When you throw a football and the wind is blowing from right to left, you throw the football into the wind. This way the wind will push the football to the desired receiver.

When calculating wind, you have to determine first what direction the wind is traveling. This is in reference to your location to the target. Using a clock method, the target will be at the 12 ‘O’ clock position.


----------



## Diamondback 2/2 (May 5, 2009)

The reason we must understand the direction of the wind, is b/c it directly impacts the value of the wind. If the wind is blowing right to left (3 to 9 ‘O’ clock) it would be considered a full value wind. If the wind is blowing at an angle say 1 to 7 ‘O’ clock it would be considered a 1/2 value wind. These are the values of the wind reading you take. Meaning if you are getting a reading of a 10MPH wind and it is at a 1/2 value, you would only adjust for 5 MPH of wind (the 1/2 value of the actual wind).


----------



## Diamondback 2/2 (May 5, 2009)

Now getting the wind reading can be done using several different methods, observation, mirage, feeling and the pointing method are the most common methods.

*0-3 mph: Wind hardly felt, but smoke drifts 
3-5 mph: Wind felt lightly on the face 
5-8 mph: Leaves are kept in constant movement 
8-12 mph: Raises dust and loose paper 
12-15 mph: Causes small trees to sway*


----------



## Diamondback 2/2 (May 5, 2009)

(A)	There is smoke or dust nearby, allowing you to measure the wind by how fast it is drifting, or (B) It is a hot day and there is an object with a well defined horizontal edge near the target on which you can see the mirage. "Mirage" refers to the heat waves which rise off of hot objects. It is easier to observe in a 50x spotting scope than in a 10x rifle scope, but it is still visible. You can see it with your naked eye if you look across the hood of your car on a hot day. In still conditions, heat waves appear as wavy vertical lines. Five mph winds bend them over at about a 30º angle while ten mph winds bend them over at about a 60º angle. Fifteen mph winds bend them over flat so it is no longer feasible to measure the wind speed this way. If you look at a horizontal edge, like a rooftop, the heat waves seem to be running along it.


----------



## Diamondback 2/2 (May 5, 2009)

If there is a large parallel component to the wind (it is blowing mostly towards or away from you), then the angle of the mirage still measures the perpendicular component of the wind, but the parallel component will make the heat waves wiggle. This is called a "boiling" mirage and is a difficult shot because a wind's direction shifts more often than it's magnitude shifts, causing the perpendicular component to vary more rapidly than if the wind were mostly perpendicular, and those changes are hard to see because of the wiggle. In cases like this it is not possible to dial your windage up and down fast enough to keep up with the variations in the wind, so you should set your scope for the least wind that you are seeing and then fire the next time the wind dies down.


----------



## Diamondback 2/2 (May 5, 2009)

Condition (A) is easy to obtain at any public range because there are always lots of people blasting away at fifty and hundred yard targets. Condition (B) is easy to obtain at rifle matches because you can look at the target boards. In combat, condition (A) is obtained in bombed out cities while condition (B) is obtained in still intact cities. You must practice with both.


----------



## Diamondback 2/2 (May 5, 2009)

Unfavorable conditions are when neither (A) or (B) are obtained, in which case you have to resort to looking at the greenery. Roughly, when grass sways and leaves flutter, there is a five mph wind. When tree branches sway, there is a ten mph wind. When small trees sway, there is a fifteen mph wind. What is most unfavorable about this technique is that the swaying of tree branches tells you nothing about the direction of the wind. For that you need another technique, the best one being to throw some grass up in the air. If 0º is perpendicular to your shot and 90º. is in line with the target (it doesn't matter if it is towards you or away from you), then assign full value to any wind from 0º to 45º. Assign half value to any wind between 45º and 75º. Ignore winds between 75º and 90º


----------



## Diamondback 2/2 (May 5, 2009)

This is a pretty good read as well...

http://www.defensiveedge.net/articles/READING THE WIND.pdf


----------



## skeeter (May 5, 2009)

Ok that helped me out A TON! the wind values really helped! Thanks:).   Is there any mathmatical solution on the adjustment for certian wind readings? I know the wind will be different at the target than it is at the location of the shooter.


----------



## Diamondback 2/2 (May 5, 2009)

Well first you have to understand Minute of Angle or MOA.

Minute of Angle: A minute of angle (a term used to discuss shot dispersion) is the standard unit of measurement used in adjusting rifle sights and other ballistic-related measurements. It is also used to indicate the accuracy of a rifle. A circle is divided into 360 degrees. Each degree is further divided into 60 minutes; therefore, a circle contains 21,600 minutes. A minute of angle is an angle beginning at the muzzle that would cover 2.54 centimeters at a distance of 91.4 meters. When the range is increased to 182.8 meters, the angle covers twice the distance, or 5.08 centimeters. The rule applies as range increases-7.62 centimeters at 274.2 meters, 10.16 centimeters at 365.6 meters, and so on.


----------



## Diamondback 2/2 (May 5, 2009)

Increase of Shot-Group Size: Just as the distance covered by a minute of angle increases each time the range increases, a shot group can be expected to do the same. If there are 2.54 centimeters between bullets on a 25-meter target, there will be an additional 2.54 centimeters of dispersion for each additional 25 meters of range. A 2.54-centimeter group at 25 meters (about 3.5 minute of angle) is equal to a 25.4-centimeter shot group at 250 meters.


----------



## Diamondback 2/2 (May 5, 2009)

Then you will need to know the deflection in MOA’s to the particular bullet at distance and wind velocity. 

For example: 10MPH full value L-R at 200 yards with M855 is 2MOA deflection, meaning your bullet will be pushed 4 inch off center zero to the right. (so you would adjust 2MOA to the left)


----------



## skeeter (May 6, 2009)

Ok... So if I understand what you are saying this will come with shooting the same bullet weight and powder charge and learning what my rifle will do at different distances, from there I can log what happened and use it next time I have the same variables.


----------



## Diamondback 2/2 (May 7, 2009)

No, it is easy to pull the data from the net or where ever else… I just can’t give you data with out knowing what bullet you are using… ;)

First things first, learn how to call the wind correctly. The rest is easy! ;)


----------



## skeeter (May 8, 2009)

Ok I understand... And before I ask for data I will need to get a rifle capable of shooting long ranges and figure out what bullet I'm using... lol :uhh:


----------



## Diamondback 2/2 (May 8, 2009)

Well the deflection rate will very from ballistics, so yeah you will need to figure out what set up you want first.

Most of the data out there for LR guns are going to be on .308 and 300WM. I would start with your budget, then move onto the type of rifle you can afford to shoot (not just buy). A lot of people buy rifles they can not afford to shoot, in LR shooting you can expect to spend $1 to $1.50 a round for good quality ammo.


----------



## skeeter (May 11, 2009)

Lol thanks J.A.B.


----------



## parallel (May 15, 2009)

+1 on that being excellent J.A.B. I learn something just about every time I log on here.


----------



## skeeter (Jun 22, 2009)

Thanks dusty... that blew my mind!


----------



## Ghostiger7 (Oct 1, 2009)

learn to read the mirage:)


----------



## Gewehrsmann (Oct 9, 2009)

Jab, that was an excellent discussion on wind.  

Skeeter, there is a mathematical formula for wind.  Using the techniques discribed by JAB to determine the speed and direction, the formula is:
Range X Wind Velocity/10  this will give you the amount of minutes of windage adjustment to apply to your scope.  I am going off memory here and am over 30, so my memory might be off but this is the formula taught us back in the day using the M21 so the round would have been the 7.62 and white box match which I think was the 175 grain FMJ.


----------



## Gewehrsmann (Oct 9, 2009)

You can use other numbers as the denominator such as 15 for a fast sleek round like the 6.5 x 284.  You will need to experiment around a bit but once you have a load and formula you should be good to go.  You might also look at some of the score books and other data sources that the high power shooters use.  They have charts and diagrams on the back cover which might be helpful.  

These techniques will only get you close to develop any level of expertise it will take thousands of rounds of practice and varying ranges and wind conditions.


----------



## skeeter (Oct 12, 2009)

Well... I'm using a .308 and have gotten a set of comp dies from RCBS. My Dad and I are working on loads using 168grn. and 175grn. serria HPBT matchkings. We go out along with Frisco this weekend maybe out to 600yds. Wish us luck;)


----------



## Etype (Oct 1, 2010)

Here's the only formula I use- The Short Wind Formula 
This is used for determining MIL HOLDS which I believe to be superior to dialing (but don't forget to dial spin drift beyond 600m) and more combat relevant because they are faster and allow the shooter or spotter to make changes on the fly as conditions change...  
.308 (M118LR)
1. Take the range and put a decimal after the 3rd digit   ex.  300m becomes .3/ 350m becomes .35  
2. Think of your wind in 4 mph blocks.  4 mph=1, 8mph=2, 12mph=3, etc...
3. Multiply your range decimal by the wind blocks.
ex. 300m target with 4 mph wind    range=.3  wind=1     .3 x 1 = .3 mil hold
ex2.  450m target with 6 mph wind   range=.45 (I'd round to 5 because I'm not that smart) wind= 1.5 .5x1.5= .7 mil hold.

Do it a couple times on the range, you'll find it to be VERY accurate!!!
For Mk262/.223, use 3 mph per wind block
For A131/.300 use 5 mph


----------



## Mic Shawn Bon (Oct 12, 2010)

OUTSTANDING JAB.  Skeeter, after determining value and velocity, you apply the forumla given above.  However, keep in mind there are constants based on range for the formula.  There may be other math-tacs to use, but I have tested this formula with constants out to 1000 yards with up to 18 mph full values.  I train under Marine Scout Sniper and Army B4 Steve Suttles.  They run a great 4-week POI.  I have two more weeks of schools to finish under him (we use up to a 6 week sniper POI on our Team, but we don't have the luxury of attending the training in one lump so we complete it in week phases).  He is an outstanding teacher and awesome at wind calls.  I just completed a phase including KD and UKD (100-1000 yards) with INSANE winds.  So I got schooled! LOL

Suttles advice: PRACTICE PRACTICE PRACTICE.  He says throughout your normal day activities, watch the environment and practice calling wind.  Go out to the ranges or fields or cities and watch mirage through your spotting scope to get better.  My first recommendation is to get you a spotter under these conditions.  It helps save rounds. LOL  I came from a SWAT sniper background before going to long range school and we RARELY use spotters on call-outs.  This is generally because real time operational deployments rarely afford the luxury of you and your spotter arriving on scene at the same time.  But after working with spotters extensively at these schools, I wish I could keep a spotting trunk monkey in my car. LOL  Anyhow, here is what we use. 

Range (100s) X Velocity (MPH) DIVIDED BY Constant = MOA Full Value
------------------------------------
Constants:
100 to 500 yards  - 15
600 yards - 14
700 to 800 yards - 13
900 yards - 12
1000 yards - 11

I wouldn't have thought the constants would have made THAT much of a difference in my ignorant days (still in those days too =), but they do at extended ranges.  If its a half value, of course just split the MOA.  You always have MIL lead cheats too, and there is DOPE out there you can use as a guideline to start comparing.  But of course you will have to figure out what your baby likes.  I go to my next phase with moving targets at extended ranges with more INSANE wind the first week of November, so I will share that experience when I get back.  Be safe brother.


----------



## Diamondback 2/2 (Oct 14, 2010)

Wow I have not been back here in a while….. Etype and Mic good stuff, the only thing I would add is that your constants will change based on your ammunition velocity. In a basic term the more bullet velocity you lose the lower amount your constant will become. However, when shooting at 1000yds and in some ammunition will allow a straight constant such as using M118, M118LR, and M852 the constant is 10 at all ranges.


Skeeter, with the ammunition you are running you will be GTG using a constant of 10, so the math is the distance times the wind speed divided by 10 giving you the MOA for adjustment. For example 5MPH full value wind speed at a distance of 200 yards (2x5=10/10 = 1MOA) so your adjustment would be 1 MOA into the direction of the wind.


----------



## Diamondback 2/2 (Oct 14, 2010)

Another option (if you’re not running a mil-dot optic) for closer ranges such as 200 to 500 yards is using aim points, for instance taking the target and breaking down into hold off points. Breaking down the human size target into 4 inch blocks as seen in the picture.


----------



## skeeter (Oct 14, 2010)

Thanks for the info guys! I haven't been able to go out past 300 yds yet because I don't feel my scope adjusts correctly. I just don't want to waste the ammo. I picked up a set of Night Force 20 MOA bases and put them on. I've also worked with dad and my rifle loves 168grn hornady A-max bullets with 42 grains of Re-loader 15 packed into Winchester brass. We also have great loads with 175 and 190 grn Serria Matchkings. I've been hanging out at the local 1000 yard matches and talking to shooters about wind. Whenever I upgrade my scope I'll get out there and try myself.


----------



## Etype (Nov 6, 2010)

Out to 300 you should be using hold overs, I'd say.  Dialing is too time consuming for combat use unless you're firing a long range, uncompromised, deliberate shot.  After bullets start flying, or on a short shots (600 and in) you should be able to do a quick mil (or guess, my favorite) then send it with a mil hold.


----------

