Range Estimation and Windage with Mil Reticles – Part 2, by N.E.
(Continued from Part 1. This concludes the article.)
Windage
Ranging distance is pretty straightforward with practice. It also becomes fairly easy to calculate your elevation adjustment in relation your data-card or ballistics app. How long-range shooting becomes an art is trying to calculate the wind.
I am going to be straight with you and say reading the wind is an art that can only be learned over time. Calculating wind becomes easier with specific calibers (high BC), the use wind meters, and lots of practice. But, calculating the wind is not nearly as straight forward as ranging distance. There are several ways to calculate wind, and one of the most basic comments that people offer is “look for the mirage.”
Learning how to read mirage is certainly useful, but I am only going to touch upon the technique here for a couple of reasons. One being, mirage flattens out around 12 miles per hour. Two, mirage does little for you on a cloudy day. Three, you are going to get the most out of learning how to read mirage through in-person instruction and lots of practice. There are all sorts of videos on the internet that talk about mirage, so I would suggest that you research those for further instruction.
The most basic benefit of learning how to read mirage is that it allows you to see what the wind is doing down range, and which direction the wind is traveling.
Yet, for those of us who desire something a little more concrete on ways to read the wind during practice, we can use a wind meter such as a Kestrel. And just as there is an equation for ranging distance, there is also an equation for calculating wind.
For this equation, I am drawing from Todd Hodnett’s quick wind formula. For those of you who are not familiar with Todd, he is second to none when it comes to long-range instruction. The quick wind formula is widely available on the internet, so there should be no issues repeating it here. For each variable in the formula, I will further explain each parameter below.
The quick-wind formula is:
Range X (wind/BC) = adjustment.
Range in the Quick Wind Formula
The way in which range is broken down in the quick-wind formula is shown in the table below. At every 100 yards, distances are broken down into decimals by one-tenth increments out to 600 yards.
100 yards =.1 | 200 yards = .2 | 300 yards = .3 | 400 yards = .4 | 500 yards =.5 |
600 yards =.6 | 700 yards = .8 | 800 yards = .9 | 900 yards =1.0 | 1000 yards = 1.1 |
Notice that at 700 yards that we add a plus one to each distance between 700 and 1000. Why this is done is a more detailed explanation than needed for this article, and trying to explain it may distract from the goal of getting on the range to practice these techniques. I can assure you from experience that you will see results from using this approach. If you are interested in the finer details I would again encourage you to look up Todd Hodnett.
Wind Speed and Direction
The next parameter in the formula is for wind. For this, we are using our wind meter to calculate the speed of the wind. The big point here is to understand the direction the wind is coming from in relation to the direction you are sending your projectile. So, be mindful of mirage if you know how to, and you can also look at how the wind is impacting vegetation, the feel of the wind on your face, or place a ribbon on a stand.
To further illustrate, let us say that we are shooting in the direction of due north (12 O’clock), and the wind is coming directly from the east (3 O’clock). This would give us a full value wind which means that the wind is pushing our projectile from a full 90-degree angle.
Yet, there are many times when the wind is coming from a 45-degree angle or 25 degrees in relation to our shot. In these examples we have full value wind (90 degrees), half value wind (45 degrees) and quarter value wind (22.5 degrees).
You can go more in-depth with the degree of angle and how the wind direction is impacting your shot, but for the early stages of learning, let us stick to a more simplified value of full, three-fourths, half and quarter value.
I am going to refer back to wind direction in the “Putting it all together” section. For now, just be mindful that the direction the wind is moving can greatly impact your calculations.
Ballistic Coefficient
The next parameter in the quick-wind formula is ballistic coefficient (BC). What is the BC? A simplified way to understand what the BC means is to think of the number listed for the G1 BC for the projectile you are using as wind in miles per hour for that particular bullet.
For instance, if we look at Federal Gold Medal Match in .308 using a 175 SMK projectile, the G1 BC for that bullet is listed as .505. We can simplify this by saying that particular bullet is a 5 mile per hour bullet. So, check your listed BC and round to the nearest whole number and translate that number into miles per hour of wind. For now, and with the quick-wind formula, there is no need to get caught up in the scientific jargon of the BC for the purpose of this article.
Putting it all together
Now that we have a basic outline for how each parameter is defined in the quick-wind formula, let us put everything together.
Returning again to the first deer we ranged at 322 yards, that deer is now to our north (12 O’clock). We round that distance of 322 yards in the quick-wind formula to .3 (could also try .32 if you wish). The wind meter is telling us the actual wind is 5 mph coming from the east (3 O’clock/full value wind), and we are using the .308 175 SMK with a BC of .505.
The equation would look like this:
.3 range X (5MPH wind/5 BC) = .3 wind adjustment to the right due to the wind coming from the east and pushing the projectile west.
Does this seem pretty straight forward? Let us try another:
The target is again to our north and was ranged at 870 yards in a 7 MPH easterly wind (full value wind). Remember that starting at 700 yards we add a plus one for every hundred yards. In this case, our formula looks like this:
.97 X (7/5) = 1.358 clicks of adjustment to our right.
Seem easy?
Returning to wind direction
As I talked about wind direction above in relation to our shooting position, we would also need to account for that by multiplying the wind angle to the MPH the wind is traveling.
Doing so is not too difficult and by repeating our last wind call which was 1.3, we would multiply this answer by a .75 (three-quarter value), .50 (half value) or .25 (quarter value)
So, 1.3 mils of adjustment is a full-value wind call, but if our wind is actually a half value wind then our windage adjustment would be cut by half to equal: 1.3x.50 = .65. This translates to 6 or 7 clicks depending on how you round the number and gusts of wind at the time of the shot.
Should this last step seem complex, then you may benefit by further researching “wind rose” on the internet for more detailed instruction. But, do not be afraid to experiment.
Conclusion
There is a lot packed in this article, and there is certainly more to learn with calculating wind than what is written here. I have found that overwhelming people with too much information too soon is counter-productive. If you follow the basic steps in this article, you will see results down range out to 1,000 yards.
Once you begin practicing, you may realize that doing all of these calculations takes time. However, the more you practice, the faster you can calculate your elevation and windage. Another aspect I enjoy with this style of shooting is that you can spend two hours at the range and only shoot about 50 rounds. This is nice if you enjoy spending time at the range without breaking the bank.
It also seems to be common for people to think that shooting deer is unethical at longer distances. I think this is an outdated concept if you have the skill to hit your target consistently. If you can hit a pie plate 10 out of 10 at 500 yards, then 500 is your max effective range if you are using a properly suited caliber for that distance (5.56 isn’t going to cut it). Proceed with integrity when using this information.
This article was written in the spirit of recreation and reintroducing the importance of marksmanship in modern firearms discussion. All of this information is widely available in bits and pieces on the internet, and you can buy and use all sorts of electronic devices that aid in achieving accuracy.
However, when thinking about American traditions and values, being a skilled marksman was once high on that list. This article is an effort to inspire community bonding with like-minded people that enjoy being outdoors, and American traditions. I hope to see you on the range!