Can someone explain MOA and how it helps for dummies?

Zapawaf, your post's tone sounds trollish. However, to give you the benefit of doubt:

http://www.shootingtimes.com/2011/01/03/optics_moast_040407/

I think this article is about as "dumbed down" as it gets.

MOA is minute of angle and refers to the mechanical accuracy of the gun. 1 MOA equals 1" groups at 100 yards. So if you have a gun (and ammo) that shoots 1 MOA then you are mechanically capable of 1" at 100yds, 2" at 200yds, 3" at 300, etc... So if you, the human, shoot perfectly that is what you would get out of the rifle.

For example my Stevens shoots about 1.5 MOA. I get 4.5" groups at 300 yards, sometimes smaller (luck) and sometimes larger (me screwing up).

Maybe that will help?

In simple terms, a 1 MOA scoped centerfire rifle has been a very allusive beast for most of the last century.
I'm not talking about one that shot a 1 MOA 3-shot or 5-shot group week before last year, once.
I'm talking about one that will do it consistently every time you try to do it.

If you had one not that many years ago, you had the best the manufactures had to offer, and also got lucky when you bought it.

More recently, improvements in barrels, action lock time, bedding, and most importantly, bullets, have made the 1 MOA rifle commonplace.

But still not every one you buy will do it.
Regardless of what you read on the liernet!

The other thing is, lots of rifle barrels will shoot 1 MOA with select loads, and a cold barrel.
But finding one that will do it for 5 shots, or 10 shots, with a hot and getting hotter barrel is also hard to do. That would indicate the barrel is stress free and isn't warping as it heats up.

MOA is a test of a rifle & a loads accuracy everyone can measure fairly accurately with common tools, relate to, and compare.
And it's the only standard one we have.

Other then that?
I don't know what to tell you.

rc

Regardless of what you read on the liernet!

Click to expand...

Everybody knows all the internet people go to their own range and that's why nobody else sees all those great groups.

MOA is minute of angle and refers to the mechanical accuracy of the gun. 1 MOA equals 1" groups at 100 yards.

Click to expand...

MOA correlates to 1.047" at 100 yards. A 1" group is sub-MOA.

This is just about the best I have read.

http://riflestocks.tripod.com/moa.html

Zapawaf,

Here is a really good youtube video on it. Oddly enough called MOA for dummies...

http://www.youtube.com/watch?v=VA2PZBD5Tjg

I suppose you could call an inch at a hunnerd moa, but you'd be wrong.Refer to taliv's post.

Heh, well, it actually took me a bit of searching to find it too, another member had posted it on these forums.

Check out the rest of that groups videos. Learning how to mount my scope was really easy using the video they have for that too.

Back to high school math.

Do you remember similar triangles and isosceles triangles from high school geometry?

In your math notebooks, draw sketches of the triangles which I will describe and label the length of each side of the triangles.

Imagine that the muzzle of your rifle is at the peak of a long, very skinny isosceles triangle whose equal sides are 100 yards in length. The very sharp (acute) very tiny angle at the vertex at the muzzle is (1/60)th of 1 degree, which is 1 minute of angle (1 MOA)

The very short (a smidgeon over 1 inch) base of the triangle is 100 yards away and is parallel to the firing line. If your rifle fires a group that is as wide as the base of that triangle, then your rifle is shooting a group that measures 1.00 MOA.

Similar triangles have the same angles and same overall shape, but can be scaled to different sizes. So if we make all the sides of the long skinny isosceles triangle 1/2 as long, the short base of the triangle will be 50 yards away and it will be (1/2)" (plus a half a smidgeon) long. So at a range of 50 yards, 1 MOA = .50 inches.

Now go back to the original 100 yard long isos. triangle. Multiply all sides of the triangle by 2. Now the equal sides of the triangle are 200 yards long, and the short base of the triangle is 2" (plus a double smidgeon.) long. So at a range of 200 yards, 2 MOA = 2.00 inches (plus a little bit)

Likewise, 1 MOA at 25 yards = .25 inches; 1 MOA at 250 yards = 2.50 inches; and 1 MOA at 300 yd = 3.00 inches. (It's generally acceptable to forget about the smidgeons and little bits which are required to make it perfectly accurate.)

I hope you all payed attention and took notes. Because when you come back to my class from Thanksgiving vacation, I am going to give you a surprise "pop" quiz on the topic.

Next week, we will stretch our minds a little bit, and define 1 MOA cones instead of triangles. Now Fred, quit fooling with Rebecca's hair. You don't stand a chance with her, anyway. [Muffled laughter.]

Have a great Thanksgiving! Class dismissed!

Sometimes pictures help.

I had to teach this in the army. I think I can help make it a little simpler. Lots of folks on here got it, but I'll throw another explanation in too. Sometimes having a few different explanations saying the same thing but worded different helps. I also studied math at university, so I know how to explain things without using much so context isn't lost.

MOA, or minute of angle, is a mathematical term. Imagine a pie with slices. Each slice is so many MOA depending on how wide the slice is. Now as the slice gets longer, as the pie grows in diameter, you notice that it also gets wider. So in shooting, the length of the slice is the distance you shoot at, and the width (and height) is size of your group. Now notice if the group is one size at one distance, you can expect that group to be wider at longer distances.

Imagine setting up targets at 100-600m such that when you shoot a group into the first target, the targets are lined up so that the group will print on the others. Assume the group at 100m is about 1", so about 1MOA. Then at 600m, you'd have about a 6" group and that would be about 6MOA. Why this is important is because if you have a rifle that shoots 1MOA, it means you will never consistently shoot groups better than about 6" at about 600m. Say the rifle shoots 2MOA. Then you just multiply the MOA by the yardage or meters and get a close estimate of the size of the group at 600m. For about 2MOA, you get about 12" groups at 600m.

To use MOA... MOA is a form of measurement. A scope or iron sight such as the A2 sight on an M16 is graduated in MOA. Say I have a scope with 1/4MOA adjustment on a rifle that is capable of consistent 1MOA groups. Then if I shoot a group at 100m and it is one inch to the right, I may move left four clicks, or 1MOA, which correlates to about 1" downrange on the target. Assume there is wind at 600m and I want to make an adjustment. I determine that the wind will push my round about 12" at 600m. To make the adjustment on my scope, I go from inches to MOA. Since 6" is about 1MOA at 600m, then 12" would be about 2MOA, so I adjust my scope 8 clicks, since it is in 1/4 increments.

MOA is a mathematical term, so there is no way of getting around that. But you can use it simply to your advantage. To adjust up or down, you basically do the same thing I said for windage. If you are six inches high at 600m, you need to go down 1MOA. Conversely, if you are six inches high at 100m, you need to go down 6MOA. Basically, MOA translates the size of a group in inches at a given distance to another form of measurement in MOA that allows one to talk about changes in the scope's setting at any range.

Imagine if the sights and scope were graded in inches. Then if you shot a group at 100m, how would you be able to correlate that group or make adjustments for a group at 600m? You can't, not without using MOA, and so that is why it is used.

Finally, I say "about" through here because 1" is "about" 1MOA at 100y or 100m. If you have a rifle that shoots 1MOA, there is enough error here to just use 1" = 1MOA at 100m or yards.

I'm guessing you found pictures or videos by now, and that combined with these explanations should help, should get you started. Learning MOA and how to use it naturally is a big plus toward becoming an excellent shooter, is how we discuss things in long range shooting and collect data at different ranges with different rifles using different ammo, etc.

Don't be put off by the math. Instead, learn the basics of it in the context of shooting, memorize it, and practice it at rifle ranges. Note because it is a mathematical term and we do use it in that context, a simple Google search for "MOA" is likely to turn up a bunch of stuff with trigonometry and algebraic expressions. You don't need to worry about this. Instead, search for stuff about MOA with shooting or long range or some such as part of the search criteria. Hope this helps, good luck.

Yes, that picture says it. Use it and toy around with it and ponder the situations I presented. Then go practice it and see it work on the range.

It REALLY helps to have someone that understands this with you at the range. If you were to talk to a range safety about it at a range with one of those, I bet they could help you out too.

Zapawaf said:

So I guess my question now is, if I was shooting at a target 500 yards, (in a perfect world with no wind whatsoever) could I use MOA to determine how far above the bullseye I'd have to shoot to get it dead on? Or is there a whole lot more to it?

Click to expand...

There's more to it. To estimate drop you need to refer to a ballistic table. Keep in mind that once it leaves the muzzle the bullet is accelerating in a downward direction. That means the drop from 400 to 500 yards is more than the drop from 100 to 200 yards. The bullet is slowing down at the same time aggrevating the problem. Crosswinds act on the bullet the whole time it's in flight.

Drop isn't hard to figure out at the range. Knowing how to dope the wind for shots over 300 yards or so separates the so-so shooters from the good ones.

You know how there are 360 degrees in a circle? Well, degrees are too large of a unit to measure shot groups and sight corrections... a 1 degree angle is 5 feet wide at 100 yards. So what we do is break those degrees down into smaller slices. Just like how there are 60 minutes in an hour, there are 60 Minutes of Angle (MOA) in every degree. It is a very fine unit of measurement that is suitable for precision marksmanship.

The 2 things we measure in MOA are the size of a shot group, and sight corrections. Both involve angles. When you are measuring shot groups, you are measuring the angle of the variation in bullet spread that a rifle fires, to see how accurate it is. For sight corrections, you use angles because when a rifle is not zeroed, it means that the sights are aimed in one direction and the barrel is aimed in another. You use minutes of angle to figure out what angle the barrel is from the sights, so you can move the sights the right amount of MOA to get on target, and bring that angle to zero.

If you really want to see this explained well, go to an Appleseed marksmanship clinic. You will learn a lot. www.appleseedinfo.org

Anyone with a high school age son should encourage them to work for a surveyor for that summer job rather than bag groceries. Old ladies raising cain about their eggs can get pretty nasty, but stomping through briars, copperheads and yellow jackets will teach real work ethics and they’ll learn something useful like angular measurement (deg, “, ‘).

You guys are making things to difficult. There are only 2pi radians in a circle. Since a circle with a 100yd radius has a circumference of 22,619.5 inches then each inch of that represents 2pi/22619.5 or 0.000278 radians.

Oops, wrong units.

What I meant to say was 1 inch of the circumference of a 100yd radius circle is 1/22619.5 of 360 degrees, or 0.0159 degrees. Multiplied by 60 minutes in a degree gives 0.954 minutes of an angle for 1" at 100 yards. Conversely, 1 minute of a degree is 22619.5/360/60 or 1.047" at 100 yards.

Now, can it get any simpler than that?

Thanks esheato, for the the excellent diagram you provided.

This is what connected the dots for me...say your scope has 1/4 MOA adjustments.

Each click adjusts 1/4 MOA...no matter the distance. 1/4 MOA = 1/4 MOA. The adjustment has nothing to do with inches...get it out of your head now.




Looking at the graphic, at 100 yards, 1 MOA equals roughly 1" right? Break that one inch into four equal parts....each click = 1/4".

Now look at the graphic again, at 200 yards, 1 MOA equals roughly 2" right? Break that 2 inches into four equal parts...each click is now worth 1/2".

Now look at the graphic again, at 300 yards, 1 MOA equals roughly 3" right? Break that 3 inches into four equal parts...each click is now worth 3/4".

And on and on...

1 MOA is 1 MOA. And on a 1/4 MOA adjustment knob, each click value changes as the distance increases or decreases because the cone (see pic above) changes diameter.

This is the basic understanding of minute of angle. To apply it to long range shooting, you need your gun and load data, environmental data and you pump that into a ballistic calculator which spits out a drop chart. The drop chart will tell you how many MOA to dial to get your bullet on target.

In the field, I use my reticle to measure (in MOAs) how far I missed my target...not inches. I have never looked downrange and said, "I missed by about 10 inches, which equates to blah blah MOA, so that should be blah blah clicks" Let me say it again, I use my reticle to measure (in MOAs) how far I missed my target. Say I shot low.....I measure how low using my reticle and make that exact correction on the knob and pull the trigger again. Say I was a half MOA low....because my adjustments are 1/4 MOA, that means there are 4 clicks per full MOA adjustment. With a half MOA low shot, I add another 2 clicks up elevation and I should hit my target.

Now, I've simplified this a bit for clarification purposes but there are some additional concerns when buying a MOA scope for long range (reticle and knobs matching and SFP vs FFP for starters). If you are serious about buying an optic for long range, please ask before buying.

Hope this helps...

Keep in mind that once it leaves the muzzle the bullet is accelerating in a downward direction. That means the drop from 400 to 500 yards is more than the drop from 100 to 200 yards. The bullet is slowing down at the same time aggrevating the problem. Crosswinds act on the bullet the whole time it's in flight.

Click to expand...

I feel it is pertinent to mention that a bullet's velocity has nothing to do with the rate at which it descends. Assuming a perfectly flat range and a rifle fired level with the ground, a bullet dropped from the same height at the exact sime time as the one being fired leaves the muzzle will hit the ground at the same instant.

Where velocity does come into play is how far that bullet gets in the amount of time it takes for gravity to bring it to earth. What I mean is, the bullet from a .308 and a .300 RUM will both drop the same amount in a given amount of time, but the .300 RUM will have covered more distance in that time. Take a 180 gr. bullet with a B.C. of .5, 0' elevation, 60* F and 29.92 baro:

Fired from the .308 Win. at 2,700 FPS, the rifle perfectly level with the ground at 48", the bullet will impact earth at 465 yards after .61 seconds of flight.

Fired from the .300 RUM at 3,300 FPS, the rifle perfectly level with the ground at 48", the bullet will impact earth at 555 yards after .61 seconds of flight.

The higher velocity of the .300 RUM did not keep the bullet in flight any longer, but allowed it to cover an additional 90 yards in the same amount of time.

It is important to understand that higher velocity cartridges have flatter trajectories because of distance covered in x amount of time, not because increasing velocity allows the bullet to defy gravity. Similarly, higher ballistic coefficients resulting from lower drag designs make the trajectory flatter because the bullet does not slow down as quickly. It's rate of acceleration downward with the force of gravity is constant.

Wind drift, on the other hand, does have to do with bullet shape/weight, as well as velocity. Slower bullets allow wind to act on them for a greater amount of time over a given distance, but also a heavier bullet will be less affected than a lighter one with the same bearing surface. Think of it as a 4" piece of 1x4 pine and a 4"x3.5"x.75" hunk of steel; Which one do you think you can knock over by blowing on it?

At extreme range, other factors like corealis effect and spin drift come into play, but that's a much more complicated subject. Nonetheless, all of these things are related to MOA (or milliradian, if you like metric) calculations. MOA/millirad is to inches or centimeters what mass is to weight; One is dependent on other variables being known, the other is not. What I mean is, MOA or millirad is constant, regardless of distance from muzzle, whilst windage or elevation calculations in length(distance) measurements require the range to be known, just as a pound or newton depends on specific gravity, but a slug or kilogram is the same no matter what the gravity factor is. 1 MOA is 1 MOA, whether 50 yards or 5,000, just as a slug is a slug, whether on earth or venus.

I like this series of videos I think they explain things well.

http://www.youtube.com/watch?v=VA2PZBD5Tjg&feature=relmfu