You’re not going to hit your target 100% of the time. And if you are, you need to move your target further back or make it smaller. Missing the target is part of long-range shooting, but there is a way to help increase your hit probability. That is simply by understanding the errors in the system. If you know the errors and how to incorporate them into your calculations, you can increase your chances of an impact.
I can't think of the words to describe how it feels after running the formulas, and everything works perfectly with a first-round impact—maybe tantalizing?
Fundamentals
Before focusing on the more challenging aspects of long-range shooting, it's essential to have the basics down first. The fundamentals of marksmanship: Sight picture, sight alignment, steady position, breath control, recoil control, and trigger pull. If you don't have the fundamentals squared away, you're focusing and investing your time in the wrong thing if your trying to figure out spin-drift and Coriolis. I can't stress enough the importance of dry fire practice. Dryfire practice makes you a better shooter and keeps your skillset sharp between trips to the range.
Mil Formula
The first step is to determine the distance to our target. This can be done easily with a range finder. However, I like to teach the how-tos with minimum equipment. You are the weapon, and if one relies solely on equipment well, then maybe they are not that great of a shooter. Also, as I have often asked, what will you do if the batteries die or your equipment stops working?
The formula is simple:
Target size (in) x 27.77 / target size (Mils) = Distance (yards)
8 x 27.77 / .42 = 528.9 yards
The mil formula is simple and accurate for close and mid ranges. At longer ranges, it gets more difficult to mil a target accurately. With a good reticle you can measure to .1 mil. At extended ranges, it’s difficult to tell if you’re seeing .1, and anything under .1 is impossible. That small error is enough to miss the target. Using the scenario above, let’s look at how this can affect ranging.
We can see .4 or .5 mils, but we can’t see .42. Let's look at the .02 error.
8 x 27.77 / .4 = 555.4 yards and 8 x 27.77 / .42 = 528.9 leaving an error of 26.5 yards.
When correcting for drop at 528 yards, we have 3.5 mils; at 555 yards, we have 3.8 mils, with a difference of .3 mils. With an 8-inch target aiming at the center, we have 4 inches of room for error. We can use another formula to see if we have a hit or miss. This formula will tell us how many inches per .1 mil the round will move.
Range in 1/100 yards / 2.777 x Number of clicks = distance round will move in Inches.
5.3/2.777*3=5.72 inches
With only 4 inches of room for error and 5.72 inches of error due to miscalculations in distance using the mil formula, we are almost guaranteed to miss our target.
Let's look at a .1 milling error.
8x27.77/.3=740.533
8x27.77/.4=555.4
8x27.77/.5=444.32
As we can see from the examples above, milling a target is a good way to estimate the distance, but it's an estimate and may not be accurate enough for a first found hit.
Wind formula
When you listen to my podcast or read my blogs, get a piece of paper and a pencil, as some math will be involved. We’re going to revisit our wind formula. We’ll first start with an exercise. You’ll need a wind meter such as a Kestrel.
For this exercise, go outside, face into the wind, look at your environment. and guess the minimum and maximum wind speed. Next, use your wind meter to determine the wind speed. I will typically hold it up for about two minutes. Based on what your wind meter is reading, how accurate were you? This exercise aims to determine your error, meaning if you estimated a 10 mph wind and it’s actually 15 miles an hour, you know your wind reading ability is within 5 miles an hour. This is also an excellent way to train yourself to read the wind speed.
EX:
Wind speed / Gun Number x 1/1000 Distance x sine
12 mph @ 12:30
GN - 4
Distance - 530 yards
12/4x.53x.25=0.39 mils
Suppose you estimate the wind speed to be between 5 and 10 mph. However, due to this exercise, you recognize a natural error of estimating 5 mph slower than the actual wind speed. Thus, the real wind speed is between 10 and 15 mph. You must make an informed decision on whether to add 5 mph (resulting in 10 to 15 mph) or your minimum of 5 mph to your corrected estimate of 15 mph. For this example, let's conclude with a range of 5 to 15 mph and apply the formula.
5 / 4 .53 .25 = .16 mils
15 / 4 .53 .25 = .49 mils
Our correction is .2 - .5 mil for our wind hold.
For our true wind value 10-15 mph
10/4*.53*.25=0.33 mils
15/4*.53*.25=0.49 mils
As we can see, the difference is only .17 mils, but including our 5 mph wind reading error, we now have a better chance of impacting the target.
Target wind speed
Next, we are going to figure out our target wind speed. Target wind speed is the speed of the wind that it takes to push our bullet the entire width of the target. Using our reticle, we measure our target. An 8-inch target at 530 yards will measure .42 mils. Next, we’ll need our 1mph wind effect. We can build a chart beforehand (I strongly recommend this) or figure this out using our wind formula. Let’s look at our wind formula to get our 1 mph value at 530 yards.
I like to use 10 mph.
10/4*.53=1.33 mils.
This is for a full value wind. Next, we need to account for the 15º wind angle.
1.33*.25=0.33 mils
To obtain our 1 mph wind value, we shift the decimal one place to the left, changing .33 mils to .03 mils. A 1 mph wind at 530 yards from 12:30 will move our bullet .03 mils.
The final step involves dividing our target size in mils (.42) by our one mph correction, which is .03 mils.
.42/.03=14 mph
This means it will take a 14 mph from 12:30 to push our bullet the entire width of our target of 8 inches.
In short, the formula is:
Target size in mils / 1 Mph wind effect
Overview
We did it!! I know that was a lot of information and math, but I assure you it looks more complicated than it is. To simplify it, below are the formulas. It's best to memorize the formulas, but they need to be written in your D.O.P.E book so they can be used as a reference.
Mil Formula
Target SIze (in) x 27.77 / Target Size (Mils) = Distance (Yards)
8*27.77/.42=528.9 yards
Wind Formula
Wind Speed (mph) / Gun Number x 1/1000 of Distance x Sine = Wind Correction in Mils
10/4*.53*.25=.33 Mils
Target Wind Speed
Target size in mils / 1 Mph wind effect
.42/.03=14 mph
The Overwatch
Comments