MeanStreaker
10-13-11, 13:40
Even though the average third grader should be able to understand the simple math involved, Minute of Angle (MOA) can be a confusing concept to new shooters, grizzled 10,000 round per year champions, and everyone in between. Internet forums run rampant with errors and it is not uncommon to see flubs, either accidental or ignorant, in major firearm publications or from professional instructors. One slip of the tongue (or typing fingers) saying “Inches” when we should have said “Minutes” confuses everyone involved and takes us deeper down the rabbit hole towards mere rifle posers instead of Riflemen.
Seeing a few errors in recent threads, I hope you don’t mind I wanted to share the Definition of MOA and why we need to be precise and exact when discussing this concept. Hopefully this information will be useful to folks and help us all better understand MOA and its usefulness.
What is a Minute of Angle?
A Minute of Angle is simply a measurement unit of an angle. Most people are familiar with the measurement unit “Degree”, which is also a measurement of an angle. For example, it is common knowledge there are 90 Degrees in a right angle.
MOA is a much smaller measurement than a Degree. In fact,
1 MOA = 1/60th of 1 Degree
Just like there are 60 Minutes in an Hour, there are 60 Minutes in a Degree.
The Minute of Angle unit is useful to shooters because the math works out (after a negligible rounding down) that our target shot group sizes, when measured in inches, can be easily converted into MOA. That is because:
1 MOA = 1” PER 100 Yards
Take a look at the diagram below. Assume the blue angle I’ve drawn is 1 MOA. As the angle goes further out in distance from the muzzle, that angle measurement is always 1 MOA. Yep, even going out 100 yards, 1000 yards, or 1000 light years, 1 MOA is 1 MOA is 1 MOA. It never changes.
What does change is the red distance between the two blue lines that make up the 1 MOA angle.
http://i35.photobucket.com/albums/d170/MeanStreaker592/1MOApic.png
Because 1 MOA = 1” PER 100 Yards:
At 100 Yards, 1 MOA = 1”
At 200 Yards, 1 MOA = 2”
At 300 Yards, 1 MOA = 3”
…
At 1500 yards, 1 MOA = 15”
Once we have a handle on what 1 MOA is, then we can start thinking in multiple MOA to describe a rifle and shooter’s standard of accuracy. (My personal standard with my ARs is certainly not 1 MOA!)
Remember just like 1 MOA is 1 MOA is 1 MOA... the angle measurement 3 MOA is 3 MOA is 3 MOA going out in distance.
http://i35.photobucket.com/albums/d170/MeanStreaker592/3MOApic.png
Because 1 MOA = 1” PER 100 Yards:
At 100 Yards, 3 MOA = 3”
At 200 Yards, 3 MOA = 6”
At 300 Yards, 3 MOA = 9”
…
At 1200 yards, 3 MOA = 36”
Likewise, 4 MOA is 4 MOA is 4 MOA.
http://i35.photobucket.com/albums/d170/MeanStreaker592/4MOApic.jpg
Because 1 MOA = 1” PER 100 Yards:
At 100 Yards, 4 MOA = 4”
At 200 Yards, 4 MOA = 8”
At 300 Yards, 4 MOA = 12”
…
At 1125 yards, 4 MOA = 45”
Why is Understanding MOA Important?
Our rifles speak a specific language. Unfortunately, it ain’t English. Their language also isn’t Inches. Our rifles speak Minute of Angle.
If we need to sight in a rifle, we have to speak MOA.
If we need to range a target at an unknown distance, we have to speak MOA.
If we need to gauge a rifle’s accuracy, we have to speak MOA.
Thinking and speaking in inches to our equipment gets us nowhere. As we learned with the above diagrams, shot groups in inches are not helpful because they are variable depending on the distance from the muzzle. MOA are consistent.
Every one of us knows someone who was bragging about their new boomstick and said, “It shot a 6 inch group!!!”
Sorry, but that doesn’t tell me anything. If your target was at 400 yards, that’s pretty darn impressive. If your target was at 25 meters, you suck.
Similarly, we’ve all seen those guys at the range that show up with a box of ammo, fire three rounds, look at their target, scratch their head, shrug their shoulders, crank on the sights for awhile, fire three more rounds, take a look, crank the sights the other way for awhile, rinse and repeat... and leave hopefully a little more sighted in than when they arrived.
That’s a waste of a lot of ammo and a waste of an accurate firearm. Instead, understanding MOA, that same shooter could have fired one good shot group. Then, he’d measure and discover his group is 3 inches to the right of the target. Since he knows he is shooting at 50 yards, he does a quick calculation and determines:
At 50 yards, 3” = 6 MOA
Now he can adjust his sights or scope 6 MOA since that’s what sights are calibrated in (their language), and his next shot group will be in the black. Then it’s on to more serious training with the ammo he’s saved.
Understanding MOA and how it is converted to inches makes us all a bit more efficient and a lot more knowledgeable.
Seeing a few errors in recent threads, I hope you don’t mind I wanted to share the Definition of MOA and why we need to be precise and exact when discussing this concept. Hopefully this information will be useful to folks and help us all better understand MOA and its usefulness.
What is a Minute of Angle?
A Minute of Angle is simply a measurement unit of an angle. Most people are familiar with the measurement unit “Degree”, which is also a measurement of an angle. For example, it is common knowledge there are 90 Degrees in a right angle.
MOA is a much smaller measurement than a Degree. In fact,
1 MOA = 1/60th of 1 Degree
Just like there are 60 Minutes in an Hour, there are 60 Minutes in a Degree.
The Minute of Angle unit is useful to shooters because the math works out (after a negligible rounding down) that our target shot group sizes, when measured in inches, can be easily converted into MOA. That is because:
1 MOA = 1” PER 100 Yards
Take a look at the diagram below. Assume the blue angle I’ve drawn is 1 MOA. As the angle goes further out in distance from the muzzle, that angle measurement is always 1 MOA. Yep, even going out 100 yards, 1000 yards, or 1000 light years, 1 MOA is 1 MOA is 1 MOA. It never changes.
What does change is the red distance between the two blue lines that make up the 1 MOA angle.
http://i35.photobucket.com/albums/d170/MeanStreaker592/1MOApic.png
Because 1 MOA = 1” PER 100 Yards:
At 100 Yards, 1 MOA = 1”
At 200 Yards, 1 MOA = 2”
At 300 Yards, 1 MOA = 3”
…
At 1500 yards, 1 MOA = 15”
Once we have a handle on what 1 MOA is, then we can start thinking in multiple MOA to describe a rifle and shooter’s standard of accuracy. (My personal standard with my ARs is certainly not 1 MOA!)
Remember just like 1 MOA is 1 MOA is 1 MOA... the angle measurement 3 MOA is 3 MOA is 3 MOA going out in distance.
http://i35.photobucket.com/albums/d170/MeanStreaker592/3MOApic.png
Because 1 MOA = 1” PER 100 Yards:
At 100 Yards, 3 MOA = 3”
At 200 Yards, 3 MOA = 6”
At 300 Yards, 3 MOA = 9”
…
At 1200 yards, 3 MOA = 36”
Likewise, 4 MOA is 4 MOA is 4 MOA.
http://i35.photobucket.com/albums/d170/MeanStreaker592/4MOApic.jpg
Because 1 MOA = 1” PER 100 Yards:
At 100 Yards, 4 MOA = 4”
At 200 Yards, 4 MOA = 8”
At 300 Yards, 4 MOA = 12”
…
At 1125 yards, 4 MOA = 45”
Why is Understanding MOA Important?
Our rifles speak a specific language. Unfortunately, it ain’t English. Their language also isn’t Inches. Our rifles speak Minute of Angle.
If we need to sight in a rifle, we have to speak MOA.
If we need to range a target at an unknown distance, we have to speak MOA.
If we need to gauge a rifle’s accuracy, we have to speak MOA.
Thinking and speaking in inches to our equipment gets us nowhere. As we learned with the above diagrams, shot groups in inches are not helpful because they are variable depending on the distance from the muzzle. MOA are consistent.
Every one of us knows someone who was bragging about their new boomstick and said, “It shot a 6 inch group!!!”
Sorry, but that doesn’t tell me anything. If your target was at 400 yards, that’s pretty darn impressive. If your target was at 25 meters, you suck.
Similarly, we’ve all seen those guys at the range that show up with a box of ammo, fire three rounds, look at their target, scratch their head, shrug their shoulders, crank on the sights for awhile, fire three more rounds, take a look, crank the sights the other way for awhile, rinse and repeat... and leave hopefully a little more sighted in than when they arrived.
That’s a waste of a lot of ammo and a waste of an accurate firearm. Instead, understanding MOA, that same shooter could have fired one good shot group. Then, he’d measure and discover his group is 3 inches to the right of the target. Since he knows he is shooting at 50 yards, he does a quick calculation and determines:
At 50 yards, 3” = 6 MOA
Now he can adjust his sights or scope 6 MOA since that’s what sights are calibrated in (their language), and his next shot group will be in the black. Then it’s on to more serious training with the ammo he’s saved.
Understanding MOA and how it is converted to inches makes us all a bit more efficient and a lot more knowledgeable.