Basic Rifle Marksmanship (BRM) Series- What The Hell Is MOA?

What The Hell Is MOA…

And how does it apply to shooting and your AR15?

Well it’s kind of important, of course you don’t really need to know it. But you will waste a lot of ammo just trying to get your AR15 zeroed. So before we get to zeroing our AR15 we need to take a few and dive into Minute Of Angle (MOA) and in the process beef up on your math skills and your understanding of how your Iron Sights work.

This may look like a lot at first glance but it really is not. Don’t let the numbers intimidate you. The point here is to show you that while your math may be very precise, your IRON SIGHTS may not be. So pick up a pencil and a calculator and discover how much rounding and “close enough” are involved. It really is easy, I promise!

Don’t worry; I’ll give you some easy tables to help in simplifying this bit of wizardry.

So what is a Minute of Angle (MOA)?

Simply put it’s a unit of measure. Specifically it’s an angular unit of measure (talking circles here), 1/60th of 1 degree. Another way to say it is that there are 60 minutes in one degree and we are looking at one minute in that degree, 1/60th, a pretty small number.

Officially 1 MOA = 1.047” at 100 yards

Unofficially 1 MOA = 1” 100 yards

Good news is we don’t care about the official number. Here is why, at 1000 yards the size of our circle is only 0.47” larger than if we just round our MOA to 1” at 100 yards.

Here are some fancy visuals to help.

Official MOA

Unofficial MOA

4 MOA (The AR15 is no worse than a 4 MOA rifle)

Can you see how little the difference there is? I hope so because you will begin to see a trend throughout the rest of this article. Now lets get into how this effects us when zeroing our AR15.

To start off we will go over the most common zero distances, the Army 25m, the Marine 36y and the 50 yards. We will go over the how and why each click equals what it does at distances closer than 100 yards.

To start we need the base MOA values of the AR15/M16 A2/A4/M4(16”)/M4(14.5”):

If your AR is patterned after a M16A2, meaning it has a 20” barrel and a fixed carry handle (8/3 rear elevation drum), the sight adjustments values are as follows:


Front Sight: ~1.25 MOA (meaning each click will move the impact of the bullet roughly 1.25” up or down at 100 yards)

Windage Knob: ~0.5 MOA (meaning each click will move the impact of the bullet roughly 0.5” left or right at 100 yards)

Elevation Drum: ~1 MOA (meaning each click will move the impact of the bullet roughly 1” at 100 yards)

Why are these approximate? This is due to the differences in the actual front sight post measurements, sight radius etc. The MOA adjustments can get very complicated if you try and be too exact. Remember, these are IRON sights, not optics. Think of all these values as “Close Enough”.

If your AR15 is patterned after an M16A4, meaning it has a 20” barrel and a flat top upper receiver with a detachable carry handle (6/3 rear elevation drum) then the sight adjustments values are as follows:


Front sight: ~1.25 MOA

Windage Knob: ~0.5 MOA

Elevation Drum: ~0.5 MOA*

*Do you see the difference in MOA between the A2 8/3 drum and A4 6/3 drum? This is due to the difference in thread pitch of the rear sight base.

If your AR15 is patterned after an M4, meaning it has a 16” barrel* and a detachable carry handle (6/3 rear elevation drum) then the sight adjustments values are as follows:

16″ Mid Length

Civilian M4 (see the barrel cuts?)

Front Sight: ~1.875 MOA

Windage Knob: ~0.75 MOA

Elevation Drum: ~0.75 MOA

* The military M4 has a 14.5” barrel and you as a civilian cannot. Well you can but that’s a different discussion. Before you get into NFA (National Firearms Act) items and Short Barreled Rifles (SBR’s) as short as legally allowed is a 16” barrel, or a 14.5” barrel with a pinned flash suppressor equaling 16”. Also understand that the M4 is also referencing the notches cut into the barrel, “M4 cuts” which serve the purpose to attach an M203 grenade launcher to it.

*Another point of clarification here, I am lumping the M4 (16”) and all 16” “Mid Length” gas systems into this category. It may not be exact, but the point here is to also show you, that none of this is actually all that exact anyway.

For a 14.5” AR15 (M4 style- SBR or Pinned Flash Suppressor) with a detachable carry handle (6/3 rear elevation drum) the sight adjustment values are as follows:

Front Sight: ~1.75 MOA

Windage Knob: ~0.75 MOA

Elevation Drum: ~0.75 MOA

So these are the values we’ll use.

You will see the math for Exact numbers and “Close Enough” numbers. The reason for this is to help you see how little the difference actually is.

Army 25m Zero

A2/A4 25m Zero Target

M4 25m Zero Target

These targets can be found here.

Exact math:
To start with the Army Target at 25m

To get the values for each click at 25m

25m = 27y

100y/27y = 3.7 (This is our constant for 25m)

Close Enough Math:
25m is close enough to 25y

100/25 = 4 (this is our “close enough” constant)

Elevation
Exact

A2/A4
1.25 MOA = 1.25” at 100y
1.25”/3.7 = 0.337” per click at 25m

Close Enough
A2/A4
1.25 MOA = 1.25” at 100y
1.25”/4 = 0.31” per click at 25m

Exact
M4 (16”)
1.875 MOA = 1.875” at 100y
1.875”/3.7 = 0.50” per click at 25m

Close Enough
M4 (16”)
1.875 MOA = 1.875” at 100y
1.875”/4 = 0.46” per click at 25m

Exact
M4 (14.5″)
1.75 MOA = 1.75″ at 100y
1.75”/3.7 = 0.47” per click at 25m

Close Enough
M4 (14.5”)
1.75 MOA = 1.75” at 100y
1.75/4 = 0.43” per click at 25m

Windage
Exact

A2/A4
0.5 MOA = 0.5” at 100y
0.5”/3.7 = 0.13” per click at 25m

Close Enough
A2/A4
0.5 MOA = 0.5” at 100y
0.5”/4 = 0.125” per click at 25m

Exact
M4 (16”/14.5”)
0.75 MOA = 0.75” at 100y
0.75”/3.7 = 0.20” per click at 25m

Close Enough
M4 (16”/14.5”)
0.75 MOA = 0.75” at 100y
0.75/4 = 0.18” per click at 25m

Exact MOA at 25m

Close Enough MOA at 25m

Time to apply

Note- When numbers fall between 2, error on the lower click value (usually). Fire a 3 shot group and adjust again if needed.

Elevation
If we are 2” low at 25m?

Exact
A2/A4
2″/0.337 = 5.9 = 5-6 clicks (Matches A2/A4 Zero target)

Close Enough
A2/A4
2”/0.31 = 6.4 = 6 clicks

Exacts
M4 (16”)
2”/0.5 = 4 clicks (Matches the M4 Zero target)

Close Enough
M4 (16”)
2”/0.46 = 4.3 = 4 clicks

Exact
M4 (14.5”)
2”/0.47 = 4.25 = 4 clicks (Matches M4 Zero target)

Close Enough
M4 (14.5”)
2”/0.43 = 4.6 = 4-5 clicks

Windage
If we are 1.5” right at 25m?

Exact
A2/A4
1.5”/0.13 = 11.5 = 11-12 clicks (Matches A2/A4 Zero target)

Close Enough
A2/A4
1.5”/0.125 = 12 clicks

Exact
M4 (16”/14.5”)
1.5”/0.20 = 7.5 = 7-8 clicks (Matches M4 Zero target)

Close Enough
1.5”/0.18 = 8.3 = 8-9 clicks

A2/A4

M4

Do you want a 3rd way?
You can always take the distance from our “POI center” from the POA center and multiply that by either our Exact constant or “Close Enough” constant for our given distant to extrapolate what our POI center would be at 100 yards and use our true MOA values. Confusing? Lets break it down in numbers to make this easier.

Elevation
Exact

2” at 27y = 2”x3.7 = 7.4” at 100 yards
A2/A4
7.4”/1.25 = 5.92 = 5-6 clicks
M4 (16”)
7.4”/1.875 = 3.9 = 4 clicks
M4 (14.5”)
7.4”/1.75 = 4.22 = 4-5 clicks

Close Enough
2” at 25m = 2”x4 = 8” at 100 yards
A2/A4
8”/1.25 = 6.4 = 6 clicks
M4 (16”)
8”/1.875 = 4.2 = 4-5 clicks
M4 (14.5”)
8”/1.75 = 4.5 = 4-5 clicks

Windage
Exact

1.5” at 27y = 1.5”x3.7 = 5.55” at 100 yards
A2/A4
5.55”/0.5 = 11.1 = 11-12 clicks
M4 (16”/14.5”)
5.55”/0.75 = 7.4 = 7-8 clicks

Close Enough
1.5” at 25m = 1.5”x4 = 6” at 100 yards
A2/A4
6”/0.5 = 12 clicks
M4 (16”/14.5”)
6”/0.75 = 8 clicks

A2/A4

M4

Here is a work sheet provided to me by Roger Lomshek which may help you with this 3rd method.
See if you can get the same numbers?

Marine 36y Zero Target
You can see how this target rounds all the elevation adjustments.

This target can be found here.

Exact
100y/36y = 2.7 (this is our constant)

Close Enough
36 is close enough to 1/3rd of 100 which is close enough to 3 (this is our “Close Enough” constant).

Elevation
Exact

A2/A4
1.25 MOA = 1.25” at 100y
1.25”/2.7 = 0.46” per click at 36y

Close Enough
A2/A4
1.25 MOA = 1.25” at 100y
1.25”/3 = 0.41” per click at 36y

Exact
M4 (16”)
1.875 MOA = 1.875” at 100y
1.875”/ 2.7 = 0.69” per click at 36y

Close Enough
M4 (16”)
1.875 MOA = 1.875” at 100y
1.875”/3 = 0.62” per click at 36y

Exact
M4 (14.5″)
1.75 MOA = 1.75″ at 100y
1.75”/2.7 = 0.64” per click at 36y

Close Enough
M4 (14.5”)
1.75 MOA = 1.75” at 100y
1.75/3 = 0.58” per click at 36y

Windage
Exact

A2/A4
0.5 MOA = 0.5” at 100y
0.5”/2.7 = 0.18” per click at 36y

Close Enough
A2/A4
0.5 MOA = 0.5” at 100y
0.5”/3 = 0.16” per click at 36y

Exact
M4 (16”/14.5”)
0.75 MOA = 0.75” at 100y
0.75”/2.7 = 0.27” per click at 36y

Close Enough
M4 (16”/14.5”)
0.75 MOA = 0.75” at 100y
0.75″/3 = 0.25” per click at 36y

Exact MOA at 36y

Close Enough MOA at 36y

Time to apply

Elevation
If we are 3.5” low at 36y

Exact
A2/A4
3.5”/0.46 = 7.6 = 7-8 clicks (36y Zero targets claims 7 clicks for the A2/A4/M4, claiming 0.5” per click at 36y)

Close Enough
3.5”/0.41 = 8.5 = 8-9 clicks

Exact
M4 (16”)
3.5”/0.69 = 5 clicks

Close Enough
M4 (16”)
3.5”/0.62 = 5.6 = 5-6 clicks

Exact
M4 (14.5”)
3.5”/0.64 = 5.4 = 5-6 clicks

Close Enough
M4 (14.5”)
3.5”/0.58 = 6 clicks

Windage
If we are 1.5” left at 36y?

Exact
A2/A4
1.5”/0.18 = 8.3 = 8-9 clicks (36y Zero target claims 9 clicks for the A2/A4 claiming 0.5” per every 3 clicks, 3 clicks = 0.5”)

Close Enough
A2/A4
1.5”/0.16 = 9.3 = 9-10 clicks

Exact
M4 (16”/14.5”)
1.5”/0.27 = 5.5 = 5-6 clicks (36y Zero target claims 6 clicks for the M4 claiming 0.75” per every 3 clicks, 3 clicks = 0.75”)

Close Enough
M4 (16”/14.5”)
1.5”/0.25 = 6 clicks

Ready to try the 3rd way again? What was it again?
You can always take the distance from our “POI center” from the POA center and multiply that by either our Exact constant or “Close Enough” constant for our given distant to extrapolate what our POI center would be at 100 yards and use our true MOA values. Confusing? Lets break it down in number to make this easier.

Elevation
Exact

3.5” at 36y = 3.5”x2.7 = 9.45” at 100 yards
A2/A4
9.45”/1.25 = 7.56 = 7-8 clicks
M4 (16”)
9.45”/1.875 = 5 clicks
M4 (14.5”)
9.45”/1.75 = 5.4 = 5-6 clicks

Close Enough
3.5” at 36y = 3.5”x3 = 10.5” at 100 yards
A2/A4
10.5”/1.25 = 8.4 = 8-9 clicks
M4 (16”)
10.5”/1.875 = 5.6 = 5-6 clicks
M4 (14.5”)
10.5”/1.75 = 6 clicks

Windage
Exact

1.5” at 36y = 1.5”x2.7 = 4.05” at 100 yards
A2/A4
4.05”/0.5 = 8.1 = 8-9 clicks
M4(16”/14.5”)
4.05”/0.75 = 5.4 = 5-6 clicks

Close Enough
1.5” at 36y = 1.5”x3 = 4.5” at 100 yards
A2/A4
4.5”/0.5 = 9 clicks
M4 (16”/14.5”)
4.5”/0.75 = 6 clicks

50 yards BullsEye


Target can be found here.

Enough with targets that give you number. What about a generic bullseye at 50 yards?

Lets get our constant, this one is easy. We are working only in yards and in whole numbers.

Exact
100y/50y = 2 (this is our constant)

Close Enough
Ha, don’t need it this time! It’s all exact!

Elevation
Exact

A2/A4
1.25 MOA = 1.25” at 100y
1.25”/2 = 0.625” per click at 50y

Exact
M4 (16”)
1.875 MOA = 1.875” at 100y
1.875”/2 = 0.93” per click at 50y

Exact
M4 (14.5″)
1.75 MOA = 1.75″ at 100y
1.75”/2 = 0.875” per click at 50y

Windage
Exact

A2/A4
0.5 MOA = 0.5” at 100y
0.5”/2 = 0.25” per click at 50y

Exact
M4 (16”/14.5”)
0.75 MOA = 0.75” at 100y
0.75”/2 = 0.375” per click at 50y

MOA at 50y

Time to apply

Elevation
If we are 0.75” low at 50 yards?

Exact
A2/A4
0.75”/0.625 = 1.2 = 1 click

Exact
M4 (16”)
0.75”/0.93 = 0.8 = 1 click

Exact
M4 (14.5”)
0.75”/0.875 = 0.85 = 1 click

Windage
If we are 2.25” right at 50 yards?

Exact
A2/A4
2.25”/0.25 = 9 clicks

Exact
M4 (16”/14.5”)
2.25”/0.375 = 6 clicks

What about the 3rd way here?
You can always take the distance from our POI from the POA center and multiply that by either our Exact constant or “Close Enough” constant for our given distant to extrapolate what our POI center would be at 100 yards and use our true MOA values. Confusing? Lets break it down in number to make this easier.

So this is simple right?

Elevation
0.75” at 50y = 0.75″x2 = 1.5” at 100 yards
A2/A4
1.5”/1.25 = 1.2 = 1 click
M4 (16”)
1.5”/1.875 = 0.8 = 1 click
M4 (14.5”)
1.5”/1.75 = 0.85 = 1 click

Windage
2.25” at 50y = 2.25”x2 = 4.5” at 100 yards
A2/A4
4.5”/0.5 = 9 clicks
M4 (16”/14.5”)
4.5”/0.75 = 6 clicks

Finding Exact MOA per click for your AR15

Now in the end understand that all the above is merely a place to start for a basic understanding. If you really want to get your MOA for your specific rifle here is how you do it.

Pick a distance that you can shoot tight enough groups to reduce shooter error.

– Fire a 3 shot group
– Give the sight (do each sight separate) 10 clicks in adjustment
– Fire another group.
– Find the POI center of each group and measure that distance.
– Divide that measurement in inches by 10 (the amount of clicks you chose)
– Divide that number by the MOA value at that distance you shot at.

MOA at:
25y = 0.25”
50y = 0.5”
100y = 1”

If you shot at 50 yards and your distance between groups is 5″ for 10 clicks in adjustment then our math looks like this:

5″/10 clicks = 0.5″ per click

Since we know 1 MOA at 50y = 0.5″, we divide 0.5″ (change per click) by 0.5” (1 MOA at 50y) and get the MOA value per click of your rifle.

0.5”/0.5 = 1 MOA per click.

Another example

At 25 yards your POI center to POI center measures 3” on 5 clicks in adjustment.

3”/5 = 0.6 per click

MOA at 25y = 0.25”

0.6”/0.25 = 2.4 MOA per click

Since math is all about repetition here is one more.

At 25 yards your POI center to POI center measures 4” on 10 clicks in adjustment.

4”/10 = 0.4 per click

MOA at 25y = 0.25

0.4”/0.25 = 1.6 MOA per click.

That’s it!!!

After all that math, you did all that math right? Here are some easy tables for you.

Exact Elevation/Windage

Close Enough Elevation/Windage

Some extra worksheets provided by Roger Lomshek

I would also like to thank Roger, he is an Appleseed instructor and my backstop as I bounced my numbers etc off of him. Also provided the math on acquiring your exact MOA value. Much appreciated!

Edit: 2/9/2017

Why are these approximates? These is why MOA Theory vs. Reality.

4 thoughts on “Basic Rifle Marksmanship (BRM) Series- What The Hell Is MOA?

  1. I think I see an issue: It looks like this post is saying that a difference in barrel length between 16″ and 14.5″ M4-style carbines equate to a difference in sight adjustment values.

    If the same front and rear sights on both rifles are installed the same distance apart, then the angular values of all adjustments should be the same. It shouldn’t matter if the barrel is 10.3″ or 24″, as long as the front sight is installed in the carbine position, the clicks won’t change.

    Now, the guns will have different velocities, so the amount of adjustment of POA needed to change POI by a certain amount will be slightly different. But the value of one click will be the same on both – the change will be how many of those clicks you’ll need to make a correction.

    Right?

    1. Dave, I appreciate your attention to details. In theory yes. In practice, doesn’t matter.

      Directly from the article

      “*Another point of clarification here, I am lumping the M4 (16”) and all 16” “Mid Length” gas systems into this category. It may not be exact, but the point here is to also show you, that none of this is actually all that exact anyway.”

      “Can you see how little the difference there is? I hope so because you will begin to see a trend throughout the rest of this article”

      “Why are these approximate? This is due to the differences in the actual front sight post measurements, sight radius etc. The MOA adjustments can get very complicated if you try and be too exact. Remember, these are IRON sights, not optics. Think of all these values as “Close Enough”.”

      “You will see the math for Exact numbers and “Close Enough” numbers. The reason for this is to help you see how little the difference actually is.”

      I hope you see the point here. My goal is to reduce the confusion amongst new shooters especially that they DO NOT have to be exact. The difference in FSP between a mid length and carbine is ~2″ and 1.875 and 1.75 MOA under 100 yards is nothing. That was the point in showing all the numbers. To break this need for being exact with IRON sights. Especially when looking at the “M4 (16″ vs 14.5″) they fall with in the same click value. A 0.03″ difference at 25m, 0.05″ at 36y, 0.055″ at 50y and 0.125″ at 100y is not something to get worked up over. Though we will be tempted to.

      If you are worried about distance then look at it like this. Between the two, at 200y the difference is 0.25″, at 300y it’s 0.375″, at 400y you finally see a 0.5″ difference. It will take you out to 800y before you see a full inch in difference but remember the size of the group you will be seeing at 800y under the best conditions is ~15” if our AR15 Mid/M4 was actually a 1.875 MOA gun shooting 1.875 MOA ammo, but it’s not. It’s a 4 MOA gun shooting 2-4 MOA ammo. Like wise, are you shooting out to 800y with a .223/5.56 and expecting that 1 MOA difference in your FSP to make any difference at all when taking all those factors into account and shooting IRON Sights?

      Understand that the only time we are touching the front sight is when zeroing. Typically at a distance that makes such small numbers inconsequential especially when taking ammo into consideration. There will be no practical difference in practice. Why we see the click value adjustments equalling the same during the zeroing process (which this article was geared towards). Even more so at distance where group size will open up to the point that being exact will be more or less impossible and why we merely confirm our zero at distance and only make changes if a drastic difference is noted and verified after we take into account which zero we truly want. The near zero or the far zero (which I cover in the Twist and Zeros article)? We aren’t in the military so we can actually choose which we prefer.

      Plus, we don’t use our FSP for adjusting elevation after it is zeroed. We use the rear elevation drum which I only briefly mentioned in the beginning as we do not use it when zeroing our AR15’s except for placing it in the correct “zeroing position” which I cover in the How To Zero Your AR15” article. Even after that, those elevation markings become more of a starting place even if you are using a 20″ gun. Why I constantly preach for people to get out and shoot. It’s the only 100% method to know where your AR/rifle/any gun is going to hit at any distance after its been zeroed. Like wise, the only way to actually know the true MOA click value for your particular sights is to follow the method described at the end of the article.

      Guns don’t shoot like lasers. Which is the notion I am trying to dispel. Many new shooters and folks new to the AR15 don’t often know the difference between mid length and carbine gas systems nor their specific sight radius yet often obsess over the minute details of such when in reality, it doesn’t matter. Which is another reason I grouped them together. A 20″ barrel is easier to discern from a 16″ barrel.

      Trying to take the complication out of a subject that often gets over complicated by our need to be exact when exact does not = Service grade Iron Sights on service grade rifles with service grade ammo.

  2. Great article. You present the information based on the barrel length. I would think a point being missed is the difference between rifle sights and the click value is really distance between the front and rear sight. Can you provide the distance between sight so we can equate the click values to our rifles. BUIS whether pop ups or angled are common on rifles with free float forearms, of course the distance between sights varies a great deal even if the barrel lengths are the same.

    1. Erik, thanks for the question and you kind of answered why I didn’t use the distance between sights in your last sentence. I believe that it is more complicated than even that when taking into account your eye relief etc. So I chose the easiest and most identifiable characteristic of an AR15, the barrel length. Also, in that article we are looking at a very generic “accepted” MOA values that are all found on the internet and the math that can be used to figure out what the approximate values are.

      As you can see in the MOA Theory vs Reality until you go out and actually shoot your rifle, none of those theoretical numbers mean anything. Why they are merely approximates. As you can see, even changing ammunition can change your click value.

      So a long winded answer to say, I have purposely kept the articles as simple as possible to avoid confusion and paralysis through analysis and still put out useful information that helps take away some of the mystic of shooting for new shooters.

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