Among some of the niftier experiences I had back in my active duty days was learning more about nuclear weapons. I spent a year working through a graduate program in Nuclear Weapons Effects, Proliferation, and Policy.
That sounds boring, but I’m a super nerd.
Significant portions of that program meant learning how to calculate the effects of weapons by hand. Given things like the amount of uranium, type of device, and other things, we needed to figure out what would happen.
I always appreciated that making us learn the calculations was the first step. After we demonstrated that we could do it, we got to use logarithmic charts to make things significantly easier.
These charts were the end result of someone else doing all the work and putting it into an easy to read curve. All we needed to do was reference a value we were interested in and find the corresponding point on the curve. Of course, there was a little more math after that, but it was significantly faster than doing it all from scratch.
Yes, my friends and coworkers think I’m one of the scariest people they know. But that’s beside the point.
What do my experiences with calculating nuclear weapons effects have to do with marksmanship?
Mildot Math Introduction
I’ve touched on the magic of angular measurements before.
A minutes of angle is one sixtieth of one degree of a circle. With 360 degrees in a circle, there are 21600 minutes of angle.
Another way to look at this is that a circle is comprised of 2 Pi radians.
The quick version of this is to understand that a radian is another way to measure rotation around a point. A milliradian, sometimes called a mil or MRAD, is 1/1000 of a radian.
Let’s assume our target is 100 yards away. Go ahead and type .001, for 1/1000th, into your trusty scientific calculator and hit the “tangent” button. Then multiply this by 100, the distance to the target. Next, multiply that result by 36. This is inches per yard.
Tangent(.001)*100*36 = 3.6000012″
That’s the dirty way of saying that one MRAD is about 3.6 inches at 100 yards. It’s not exact, just like one minute of angle isn’t a perfect 1″, but it’s close enough to work with.
The convenient part about this is that if you multiply that by 10, it’s 36 inches at 1000 yards.
One milliradian equals one yard at 1000 yards. A six-foot object at 1000 yards is two mils measured this way.
As a bonus, milliradians work just as well with meters. One MRAD equals one meter at 1000 meters.
Here’s a quick look at the math for calculating range. This isn’t comprehensive, that’s for another post. I just want to illustrate how it works.
If you know the size of the target in either yard or meters, the math is straight forward.
If you know the size of the target in centimeters, and want your range in meters, it’s not too bad.
However, if you want your range in meters like the rest of the military does, but you’re a red-blooded American who uses inches instead of centimeters, it gets
It’s not much easier using yards and inches, either.
If you attend any precision rifle school, you’re going to memorize these formulas. Here’s the thing though, nobody really wants to be sitting out in the field punching numbers into a calculator.
There’s got to be a better way.
The Mildot Master
Let’s assume you don’t have a laser rangefinder handy, since that would have negated this whole discussion to a point.
Most of my audience is in the United States, which means we haven’t bought into using centimeters for measuring things. We think in terms of inches and yards.
That being the case, measuring our target in a reticle and then multiplying by 25.4 or 27.8, depending on if we want meters or yards, is dumb.
Like the logarithmic pressure curves I used when studying nuclear weapon effects, the handy Mildot Master is a quick reference slide rule that’s already done the math for me.
The system has two major components. The first is an outer plastic sleeve with an MRAD scale on it. There are two windows, one for determining range and one for calculating windage or drop. Interestingly, the drop/windage window also has a MOA scale on it in case your turrets are mismatched from the reticle.
The second component is the interior laminated card that slides back and forth. The card is reversible, with yards on one side and meters on the other.
Mildot Master Usage
There are really two steps to this process. If you already know the size of the target, then you need to see how many
Once you have that, find the corresponding marking for the size of the target in the left window. Slide that marking to the point that best matches what you measured. The range to the target appears just to the right.
Also handy is that the mildot master includes a simple way to estimate the angle to the target using a string and pivot point on the back. If you are not level with the target, the notches below “Target Range” give you the corrected range to target given the angle.
Remember, either aiming at an upward or downward angle affects the trajectory of the bullet the same way: you’ll need to aim higher on the target as if it was closer to you.
Once you know the range to target, you need to calculate your drop and windage for a firing solution.
If you’re on top of things, you’ve probably already got a dope card to tell you how much elevation to dial for the given range. But wind is a different story.
A lot of precision rifle shooters track their windage in terms of inches per drift at each distance given a 1 mph crosswind. So, if I know my shot will drift 2.3 inches at 500 yards in 1 mph of wind, a 5 mph crosswind means it will drift 11.5 inches.
Keeping the inner card at the same point, I look over to the right window and see that 11.5″ corresponds to about .5 mils of holdover (or dope) at 630 yards.
I just saved myself a lot of time.
Reversing The Formulas
If you remember algebra from back in school, you might remember how to reverse a formula to come to a different result. The ranging examples above, you can figure out the size of a target if you know how far it is.
The Mildot Master lets you do the same thing. If you know the distance to the target and how it measured in the reticle, you just work in reverse. In the left window, line up the distance to the target with the target range indicator. On the left, scan for the measurement you saw in the reticle. The size of the target is next to it.
Where to Get One
The Mildot Master is just one of those handy little tools to keep around. I use it fairly regularly along with my Vortex Solo R/T monocular to practice my ranging.
In the days where it seems like everyone except me has a laser range finder, I take a little pride in still practicing the old school.