How to Understand Minute of Angle
Full guide on how to understand MOA (Minute of Angle) and to compensate for the bullet drop. Learn how to calculate MOA and adjusting on the elevation turrets.
In the course of perfecting your shooting accuracy, you will hear the word MOA. If you don’t know what it is, then shooting on target will be the hardest thing to achieve. For those who know it, they realize that some calculations are crucial if you want to improve on accuracy.
Now, what are those calculations? Will they make shooting a rocket science subject? If you are asking such questions, the information below is for you. You will see how easy it is to understand Minute of Angle when we break it down into digestible chunks that will aid you in hitting the bull’s eye every time you aim.
So you are asking, what is MOA? It stands for Minute of Angle as explained in the title. Here, a minute refers to 1/60th of a degree. Think about the minutes in an hour. One minute is a 1/60th of an hour. When it comes to shooting, it refers to a tiny fraction of one angle.
Look at the circle. It has 360 degrees. Now, take out only one degree then divide it 60 times. That’s the portion we are talking about here. Despite being so small, the difference it can make in hitting the target is more than enormous.
Why Do We Need To Measure Shooting In Minutes?
I guessed right. That’s your next question. If you look at how a bullet moves, it does so in an arc which is not a perfect one. As it travels further, the force of gravity becomes larger hence the decrease in velocity. That makes the arc’s slope steeper.
You may notice that you are shooting dead on at closer targets like about 200 yards away. However, as you aim further than let’s say 600 yards, you note that you are hitting lower than the target point. The distance between where your bullet hits and the target is known as the bullet drop. It’s measured in inches.
We call the path followed by a bullet as the bullet’s trajectory. It happens in an arc, and that is why we need to measure it in degrees if we want to cover for the bullet drop successfully. That is where MOA comes in as a useful measurement.
The Relationship between MOA and Distance
MOA is not dependent on distance. If you thought there was a relation, well it’s a bit complicated here. We use MOA as an angular measurement as opposed to linear. That’s what we adjust a long range target scope on a rifle using the elevation turret. So, how do we translate MOA to a linear measurement?
Apply this rule: 1 minute (or 1 MOA) is one inch at 100 yards. One inch here is an approximation since it’s actually 1.047 inches. For shooting, we disregard the 0.047 inches and round it off to one. However, in long-distance shooting, it becomes applicable.
What does the above mean? It implies that if you make a minute adjustment on the scope, you are using, there is a 1-inch change in the bullet’s point of impact at 100 yards. On the other hand, the size in inches increases as you go further than 100 yards, but it’s still one minute.
|Distance in Yards||1 MOA Change in Size (Rounded Off)|
If you want an accurate shot after precise aiming, you need to know how to use MOA to solve the bullet drop. That means utilizing the elevation turret at the top of the scope.
Determine the Bullet Drop
Go to the range and shoot a group. Make sure you know the distance you are shooting from and the bullet drop. After that, memorize what 1MOA is at that distance. You can refer to the chart above.
If you are 300 yards away and you are three inches low from the target, that means making the necessary adjustments to go dead on in the next shoot out. 1 MOA is three inches at 300 yards. To recover for the drop, you will need to go up 1 MOA.
Having figured out that, we can now deduce a formula to help us calculate faster.
Formula to Calculate 1MOA size at any distance:
Distance to the target (yards) /100 = inches per MOA for the distance.
If you are 400 yards away, then that will be 400/100 = 4 inches.
1 MOA is 4 inches at 400 yards. That implies that you need 1 MOA for every 4 inches off the target.
If you want to use the exact measurements, then know that 1 MOA = 1.047 inches
Using the exact measurements, we can use the following formula:
(Distance to the target in yards x 1.047) / 100 = inches per MOA for the distance.
So, using the example above:
(400 x 1.047) / 100 = 4.188 which translates to 4.2 inches.
Calculating the Bullet Drop
Now that we can calculate the MOA at a given distance, how do you go about calculating the bullet drop?
Suppose the bullet drop is 40 inches from the target as you shoot 400 yards away. We know that we need 1 MOA for every four-inch drop at that distance.
Here is how to calculate the MOA adjustments we need for the 40-inch bullet drop:
Number of the bullet drop inches / MOA inches at the given distance = MOA needed
Therefore, 40 inches low / 4 inches (1 MOA is 4 inches at 100 yards) = 10 MOA adjustments on the scope
Now that you know the MOA needed to adjust to hit dead on, you can translate that to the scope by making the MOA adjustment via the top turret.
Translating the MOA on Turrets
Riflescopes come with the following specifications:
1/8 MOA turrets
1/4 MOA turrets
1/2 MOA turrets
1 MOA turrets
Depending on the featured MOA adjustment, it means that the turret will turn in such increments. Therefore, ¼ MOA turret will have ¼ increments, and the same applies to the rest.
Each time you move the turret, it clicks, and the lines below the numbers guide you. So, if your scope says it has the ¼ MOA adjustments, it means you need four quarters or four clicks to make 1 MOA. If it says ½ MOA adjustment, then you need two clicks to make 1 MOA.
For our case above, if you have ¼ MOA adjustments on your scope, to get to 10 MOA will require 40 clicks.
If 1 MOA needs four clicks, then 10 MOA x 4 clicks per MOA = 40 clicks.
If you have a ½ MOA scope, you will need 20 clicks if you apply the analogy in the last statement above.
Was it that hard? I hope not since everything can now be understood. As you can see, the calculations help you aim better as opposed to complicating the aiming setup. If it has not yet sunk in, here is a video that explains more about MOA and how to calculate it. If you have read the information above up to this point, then this video will help you see what we are talking about and apply the knowledge in the field.
If you are all set, then it’s time not to miss the target!
Article by Steve Coffman