Minute of Angle: what is it? and how to use MOA

If you spend any time in the precision rifle shooting world, it won’t be long before someone mentions MOA. We’re going to dive into a full guide on minute of angle.

Introduction
Some people call it weaponized math, which I like. But MOA is a shortened acronym used to describe a Minute Of Angle.

A minute of angle is an angular measurement similar to a degree. We know that there are 360 degrees in a circle, and we can use a compass to pan a certain amount of degrees right or left, just like when you learned orienteering in boy scouts as a kid.

A Minute Of Angle (MOA) is 1/60th of a degree, so it’s just a finer scale of measuring an angle offset. An MOA can be cut up into sixty seconds of angle, but that is getting so fine we probably don’t need to go into it.
As an angular measurement, shooters use the fine-scale to adjust their sights. In the same way pilots use degrees to adjust their flightpath, we use MOA to adjust the flight of our projectiles. I’ve been playing in that realm for a few decades now, so I’ll do my best to explain this dangerous math as best I can.

What Does MOA Mean?
As I mentioned, MOA stands in for the mouthful; Minute Of Angle. There are several other ways that shooters measure shooting corrections and deviations, the more popular being MRAD (abbreviation for Milliradian) and IPHY (Inch Per Hundred Yards). But let’s not muddy the water and stick to our subject, MOA.

MOA and Target Distance
As an angular measurement, the size of a minute of angle gets bigger as it gets farther away from you.

Imagine it like a very long orange traffic cone. When you look through the hole at the small end, it may only be one inch in diameter. But the same cone at the big end, maybe ten or more inches wide, the angle of that increase IS an MOA.

So keeping with our example, if the small end of the cone was two inches in diameter, then to maintain the same angle at the other end, it would have to be twenty inches in diameter.

Back in the old days, before laser rangefinders, people with less hair than me would use these mathematical calculations to estimate distance. If you know an average male is about six feet tall, you can use an MOA scale built into your riflescope reticle to measure how many MOA tall he is and reverse the math to figure out roughly how far away he is.
Once you know your target’s distance, you can use the exact same measuring scale to correct for the drop of your bullet at that distance. Now you might understand why they call it weaponized math.

Accuracy Measurement
MOA is the most common method of measuring or stating the accuracy potential of a rifle. If your rifle shoots five shots at one hundred yards that measure one-inch center to center, then you can call that group a 1 MOA pattern. If your group measures 1.5 inches, you could call it a 1.5 MOA pattern.

As I mentioned before, an MOA is an angular measurement that increases with distance. One MOA at one hundred yards is about an inch, but it measures over ten inches at one thousand yards.
To be precise, one MOA is not one inch. One MOA is actually 1.047 inches at one hundred yards. And 10.47 inches at one thousand yards, but until you are shooting well enough to notice a ½ inch difference in your groups at one thousand yards, you can just work with the inch measurement.

How to Use Minute of Angle While Shooting
As soon as a bullet leaves the muzzle of a rifle, it begins to drop due to gravity and aerodynamic resistance. The further away the bullet travels, the more it drops, which requires corrective action to “hold over” the target high enough to hit it. But how much should I hold over, you might ask?

Long-range rifle scopes have corrective mechanisms to adjust for that drop. It is accomplished by either holding over the target using the same MOA scale you used to measure this guy, or you can use the turret of the scope to dial the corrective angular adjustment. Continue reading here

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