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Thread: Minute of Angle Definition and Why Understanding MOA is Important

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    Minute of Angle Definition and Why Understanding MOA is Important

    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.





    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.





    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.





    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.

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    If you're trying to help people "get to the bottom" of MOA, you should at least acknowledge that 1 MOA is 1.047 inches at 100 Yards. Not 1 inch. It doesn't make it one bit more confusing. There's no need to think in inches anyway. If one cannot wrap their head around angular units of measurement, there's always the IPHY system. But, the only reason you'd want to use either MOA or IPHY is because you haven't figured out MILS yet.
    Last edited by a0cake; 10-13-11 at 14:52.

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    If you're trying to help people "get to the bottom" of MOA, you should at least acknowledge that 1 MOA is 1.047 inches at 100 Yards. Not 1 inch. It doesn't make it one bit more confusing.
    Thanks cake. Please re-read my post and you'll notice I do say there is a "negligible rounding down" to get to

    1 MOA = 1" Per 100 Yards

    If you are good enough to where you measure your accuracy at 100 yards with 0.047", then my hat's off to you. I'd like to see your world record certificates sometime.

    And I disagree with you. Call me crazy, but doing the math on the fly, to make a quick hit from a field position, it is much less confusing to use 1--2--3--4 instead of 1.047--2.094--3.141--4.188.

    I have worked with a lot of people to help them understand MOA and at first they have a hard enough time with the math in using 1". And again, hardly anyone is accurate enough, especially at first, for that negligible difference to matter.

    Quick, what's 1.047 x 12!
    Last edited by MeanStreaker; 10-13-11 at 15:00.

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    Let's say your optic adjusts at a 1/4 true MOA. By dropping the .047, you're assuming it actually adjusts at 1/4 IPHY. Now let's say your adjustment is 27 true MOA for a 1K Yard shot. Adjust for IPHY. You've just missed your target by over a foot. You are a no-go at this time, do you know why? Because understanding the difference between 1 MOA and 1 inch at 100 yards is important.
    Last edited by a0cake; 10-13-11 at 15:04.

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    The NSSF has a great video on this for beginners. (youtube)

    It's on the homepage of Accurateshooter.com too.
    "You people have too much time on your hands." - scottryan

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    Quote Originally Posted by MeanStreaker View Post
    Thanks cake. Please re-read my post and you'll notice I do say there is a "negligible rounding down" to get to

    1 MOA = 1" Per 100 Yards

    If you are good enough to where you measure your accuracy at 100 yards with 0.047", then my hat's off to you. I'd like to see your world record certificates sometime.

    And I disagree with you. Call me crazy, but doing the math on the fly, to make a quick hit from a field position, it is much less confusing to use 1--2--3--4 instead of 1.047--2.094--3.141--4.188.

    I have worked with a lot of people to help them understand MOA and at first they have a hard enough time with the math in using 1". And again, hardly anyone is accurate enough, especially at first, for that negligible difference to matter.

    Quick, what's 1.047 x 12!
    Almost 12.6"...not 12"!

    J/K...informative post even with the round off error (that's the mechanical engineer in me talking).

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    Let's keep the light saber wagging to a minimum. I think this is a better place for this discussion.



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    While the statement 1 does not equal 1.047 is true, in some cases it is probably accurate enough...

    I agree that shooting at 1,000 yards with a rifle/ammo combo capable of sub-MOA the difference matters. But at 200 yards with a rifle/ammo combo of 5 MOA the difference is probably lost in the noise.

    I agree it should be made clear what the real measurements of MOA are, but I don't see a big problem with rounding to 1 inch for the average AR15 shooter using over the counter ammo with an optic that's somewhere between 1 and 4X. It does make the calculations easier to do in your head.

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    In seeing the resultant discussion, perhaps I should have done a better job in introducing why I thought a post like this would be helpful.

    1) Everyone, at all skill levels, should have a basic, rudimentary understanding of MOA so they can quickly sight in any rifle they pick up. Let's not bring in 1000 yard bullseye sub-MOA shots. The other 99.9% of shooters need to understand MOA as well.

    2) In addition, I have read at least three or four threads in the past few days that are bubbled up to the top where people completely screw up how MOA interacts with inches and how that interacts with accuracy.

    I would humbly ask that we please not turn this thread into a discussion comparing various sighting/ranging applications (MOA vs MILs vs whatever), nor uber-precision 1000 yard shots that the vast majority of people lack the skill level and facilities to attempt.

    I see all the time how few of us can use field positions effectively on a man sized target out to 500 yards.

    I'd also like to say I respectfully disagree and this is not a "Precision Rifle" topic as everyone needs to be able to sight in their rifles and optics, even if you never shoot past 25 yards and you only run n gun.

    If anything, I debated putting this post in the new Shooter section of the forum. I of course don't plan to be a jerk about it, but I thought it would be nice to have something sort of formal with pics drawn up I could link to in a reply to help folks who misunderstand MOA elsewhere on this forum.

    Just trying to be helpful as I definitely remember growing up having zero idea the best way to sight in and what the heck that mystical "MOA" stuff was they were talking about in the gun mags.
    Last edited by MeanStreaker; 10-13-11 at 17:22.

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    Quote Originally Posted by MeanStreaker View Post
    In seeing the resultant discussion, perhaps I should have done a better job in introducing why I thought a post like this would be helpful.

    1) Everyone, at all skill levels, should have a basic, rudimentary understanding of MOA so they can quickly sight in any rifle they pick up. Let's not bring in 1000 yard sub-MOA shots. The other 99.9% of shooters need to understand MOA as well.

    2) In addition, I have read at least three or four threads in the past few days that are bubbled up to the top where people completely screw up how MOA interacts with inches and how that interacts with accuracy.

    I would humbly ask that we please not turn this thread into a discussion comparing various sighting/ranging applications (MOA vs MILs vs whatever).

    I'd also like to say I respectfully disagree and this is not a "Precision Rifle" topic as everyone needs to be able to sight in their rifles and optics, even if you never shoot past 25 yards and you only run n gun.

    If anything, I debated putting this post in the new Shooter section of the forum. I of course don't plan to be a jerk about it, but I thought it would be nice to have something sort of formal with pics drawn up I could link to in a reply to help folks who misunderstand MOA elsewhere on this forum.

    Just trying to be helpful as I definitely remember growing up having zero idea the best way to sight in and what the heck that mystical "MOA" stuff was they were talking about in the gun mags.

    Point taken, and your illustrations would definitely be helpful for a new shooter trying to understand how MOA scales with range.

    For most users, your definition of MOA will work just fine. I just wanted to point out that at a distance, it does come in to play and could realistically mean the difference between a hit and a miss. I think it's important to acknowledge that.

    Also, my statement about MOA/IPHY/ and MILS was a JOKE and was not my main point.

    Anyway, good illustrations and sorry if I rained on your parade a bit. Just don't put this on Snipers Hide, because somebody will absolutely lose their mind. LOL.

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