You hear about somebody talking about any riflescope and saying that turrets are one-quarter clicks, one quarter moa clicks or maybe you are looking at the red dot sight and you see that red dot in the middle is three moa. Most of the riflescopes owner really don’t know that what is Minute of angle (MOA). So we would like to explain in a very simple way and it is going to be very short.
What is a minute of angle?
A minute is just a fancy word for 1/60th. Think about sixty minutes in an hour and minute is 1/60th of an hour. Similarly Minute of angle is 1/60th of an angle, this angle is on a circle having 360 degrees and this angle is one of those 360 degrees. So Minute of angle is 1/60th of one degree. It is an angular measurement.
The arcminute is commonly found in the firearms industry and literature, particularly concerning the accuracy of rifles, though the industry refers to it as a minute of angle (MOA). It is especially popular with shooters familiar with the imperial measurement system because 1 MOA is subtended by a sphere with a diameter of 1.047 inches at 100 yards (2.908 cm at 100 m), a traditional distance on U.S. target ranges.
The subtension is linear with the distance, for example, at 500 yards, 1 MOA is subtended by a sphere with a diameter of 5.235 inches, and at 1000 yards 1 MOA is subtended by a sphere with a diameter of 10.47 inches. Since many modern telescopic sights are adjustable in half (1/2), quarter (1/4), or eighth (1/8) MOA increments, also known as clicks, zeroing and adjustments are made by counting 2, 4 and 8 clicks per MOA respectively. (Wiki)
One minute of angle is calculated by one inch at 100 yards (actually 1.047 inches) and it increases every hundred yards by one inch. If one Minute of angle (MOA) is one inch at 100 yards then one MOA is two inches at 200 hundred yard and similarly, one Minute of angle at 300 yards is 3 inches and so on.
So if you are sitting at 100 yards and you take your shot and falls two inches below your bull’s eye. Its two inches at one hundred yards then it is two MOA. If you are three inches below the target at 100 yards then it is 3 MOA.
WHAT IS SUB MOA?
The SUB MOA is a term which tells you about the accuracy of a firearm. A Sub-MOA rifle means a rifle which has a group of shots or an average of several groups, within one MOA at 100 yards which is one inch. It means SUB MOA rifles are quite capable of delivering a high level of quality and accuracy and shoot within one inch (One MOA) at 100 yards which is fantastic.
Turrets On the Scope
Now, Let’s look at the other thing and that is turrets on your scope. Most of the turrets on scopes come with the one-quarter MOA clicks for both Windage and Elevation. We know that one MOA is an inch then a quarter MOA is a quarter inch. So we can figure out that if we are shooting two inches below the bull’s eye, and we know that these two inches are two MOA and our turret has quarter MOA click then we simply need to click it eight times to come up to the bull’s eye. If we increase the distance then we can figure out the clicks need to come to the target.
Red Dot MOA
If you have a red dot or reflex sight which says that it has a Four MOA dot. It means that it is going to cover 4 minute of angle (MOA) at 100 yards. So the dot is going to cover four inches of your target at the distance of one hundred yards and so on as it goes further.