In this collection, we're going to talk about specific shot circumstances, what the indicators are, what our estimates are and… most importantly- what the results are. While there is no set formula that takes the place of experience, there are tools and methods to making consistent hits in a real world environment.
This scenario was a shot at 873 yards, measured with a G7Br2 rangefinder. The solution of 15 MOA provided from the unit was correct, but getting a first round impact can be very difficult in variable wind conditions. The wind call I made was a consideration based on four indicator areas.
The conditions for the first shot were as follows. Temperature: 76*F with 66% Humidity and 30.05 mb of air pressure. It was partly cloudy with no direct sun. The target was located just above the arrow in the picture.
The first step into deciding what wind hold you are going to use when executing the shot is to segment the range that the bullet will be traveling. There are three segments of importance along the flight path with an important indicator behind the target which is a corn field. See Figure 1 for this information.
The first segment is the mowed area along the fence that extends to the lone tree, there is measureable wind here and the Kestrel 3000 is giving readings of 3-7 mph, averaging at 5 mph from the 150* position.
The second segment of importance is the valley with trees along the right side of the drive. This area is approximately 300 yards of the total flight path.
The third segment of importance is a pond, the only evidence that you can see of this pond is the very green grass on the dam of the pond, but the pond is about 120 yards of the flight path length.
Recall that I mentioned a fourth indicator, and that was tall corn behind the target area. I did not state that the grass along the fore ground is a valuable indicator. While some may choose to disagree, I live on the prairie and have yet to be able to use the dried tops of fescue as a valuable indicator as it is much stiffer than the lush green spring ground cover. That rigidity causes the tops to sway in a circular motion instead of lying over with a prominent wind direction.
Next, we can talk about the data we can observe from each shot segment. The first segment is usually the easiest; you can measure it with a Kestrel wind meter since you are at that location and observe it directly. I try to measure the maximum velocity of the wind from the direction it is traveling from. I then use that information to contribute to my over all wind call based on a value system.
The biggest observable part of segment two is the trees. The wind is essentially a quartering right to left in the direction of the target. The biggest question here is what are the trees doing to that wind? Are they blocking it? Are the trees funneling the wind into a faster stream on the close side, or perhaps on the far side? In this case, it may be best to look for evidence of this on the leaves of the trees and on the ground around the trees with a spotting scope or binoculars.
What do we know about shooting over water on segment 3? The air can be cooler and denser. So, how does a body of more dense air react to a light breeze with very warm air? As a rule, in this type of situation, I have found the wind to be slower but less stable.
Let's not forget that we have other known variables in the flight path like the spin drift of the bullet caused by its rotation. This equates to about 3" of right travel. The sum of my observations across these three segments led me to hold 7" right of center on the target because the wind seemed to be steady across the entire flight path based on all of my observable indicators. Coupled with the natural spin drift of the bullet, that equates to 10" of right compensation.
I waited for stable conditions in a lull (when the wind dies) and fired one single shot at this range. Impact on the target was 5" right of the center. So what did I fail to execute perfectly?
After measuring the wind velocity at many points throughout the flight path after my shot, I found that there was no moving wind in segment 2 or segment 3. The first 250-300 yards of the flight path is the only wind segment experiencing significant movement.
I haven't gone into a detailed explanation of mirage for this scenario because I plan to do that on the following scenario. It is vitally important to try to include as much information into your wind calls as possible. It also helps to have experience at the physical range you are shooting.
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