What is sub MOA?

[JFrank]

MOA = minute of angle
You can shoot under a minute, at a minute or over a minute.

 

[mavracer]

Minutes of angle (MOA), whether 1 or 10 or 0.5, is a measure of precision, not accuracy. Accuracy is getting 10 Xs in a string, regardless of whether it's from a 1 MOA gun or a 10 MOA gun.

True but you can be precise without being accurate, it's hard to be accurate without some level of precision. Can you get 10X on target with a 10MOA gun without catching the target on fire lol.

 

[Zak Smith]

And there's that common use is to ask "How accurate is your rifle?" and the answer is 0.xx MOA, not "I managed to shoot a 190-3x but it was mostly luck."

 

[RetiredUSNChief]

Wow...lot's of good stuff here!

Soooo...I whipped out my 5th dan in Google-fu to look up a little history. Because while I understand what "MOA" is, it's history is what I didn't know.

Now, I'm not going to get into the math here (mostly because I haven't gotten into this myself), but feel free to do so yourself if that floats your boat. And if you want to bring in radians...do so yourself. It's really all the same, only not....but it is. Kinda like "kilometers" vs "miles".

Angular directions are broken down into degrees, with a complete circle being 360 degrees. A Minute of Angle is a degree further subdivided by 60. Why 360 and 60? Because reasons, that's why. Deal with it!

Remember when I said I wasn't going to get into the math here?

I lied. BWAHAHAHAHA!

Using basic math, and knowing that there are 360 degrees to a circle and 60 minutes per degree, that means there are 360 x 60 (or 21,600) minutes in a circle.

NOW...if we imagine a circle having a radius of 100 yards (3,600 inches), we can calculate the circumference of the circle, also using basic math. C = 2 x pi x Radius. This works out to be 2 x 3.1416 x 3,600, or 22,619.52 inches.

If you divide THAT by the number of minutes in a circle (21,600), you end up with 1.0472 inches. That is the ANGULAR distance along the circumference of the circle between the two points defined by the lines drawing through ont minute of arc. The actual straight line distance between those two points is ever so slightly shorter than 1.0472 inches. This means, for all practical purposes, we can call 1 MOA as "one inch at 100 yards".

Double the distance and that expands to 2 inches. Triple, it becomes 3 inches.

BUT WHY TALK ABOUT THIS IN MOA?

One site said "Essentially, MOA is used to help measure shooting in minutes since a bullet moves in an arc-shaped trajectory. The further a bullet has to travel (typically measured in yards), the greater effect gravity has as it decreases velocity. The farther away you are from a target, the lower your bullet might strike from where you intentionally aim. This is known as the bullet drop, which is measured in inches."

Which is a load of hogwash. MOA has nothing to do with "bullet drop". Bullet drop can be any amount. What matters is where the bullets (plural) GROUP relative to each other when shooting at the same point. And your point of aim starts with the straight barrel which is aimed at a target. The barrel defines the direction the bullet travels and since we're talking about lines and direction, it's defined relative to circles, which is concerned with distance (radius of a circle) and movements along the circumference of that circle (which is measured in degrees, minutes, and seconds because reasons). And this is essentially an angular deviation from the point of aim.

Outside influences affect exactly where the bullet hits (gravity, wind, rain, etc.) But the MOA is really concerned with the variation in where the bullets all impact when shot at the same point.


NOTE: THIS IS NOT ACCURACY, MEANING HOW CLOSELY THE BULLETS HIT TO THE POINT OF AIM. IT'S THE DEVIATION BETWEEN POINTS OF IMPACT FOR THE SAME POINT OF AIM BY THE GUN.

If you are aiming at the crosshaired bulls eye of a target and you are hitting 3 inches to the left, that's an ACCURACY issue. If you are aiming at the crosshaired bulls eye of a target and the bullets are producing a grouping all around the point 3 inches to the left, the size of that grouping determines whether or not you are within or without the MOA.

This is important to understand, because a gun which shoots with a very small grouping relative to the MOA can be made to reliably hit the target whenever you shoot the gun. But if you have a gun that has a large grouping relative to the MOA, then no matter what you do with aim adjustments, you cannot be assured you will hit your target every time you shoot the gun. A gun which produces a 6 inch grouping at 100 yards (six times the MOA) cannot ever be made to reliably hit the bullseye no matter how you adjust the sights or your aim.

And the MOA is defined as above: approximately 1" at 100 yards.

THAT SAID:

If you're shooting at 100 yards, sighting in exactly on the crosshaired bulls eye of your target, and you are producing a 1/2 inch grouping 3 inches to the left, then you're rifle is shooting to the left about 3 inches (accuracy) and is shooting a sub-MOA grouping (less than 1 inch).

 

[CapnMac]

If a ship's 16-inch gun can place shots within 200 yards at 22 miles south of the ship, that's pretty good precision*.
But if the target is actually 22 miles to the north, that's lousy accuracy.

LoL
Mind, when dealing with a battery of weapons, like a ship's broadside, the measurement is CEP, Circular Error Probability. Which typically measures at 50%. So, a CEP measures the circle which inscribes where 50% of the shots fired land. (To bend things further, naval rifles are expected to have an elliptical "circle"; acceptance for Mk 7 16" 50 was a CEP for a 500' x 250' ellipse-which is logical as that's "minute of battle ship." )

It's a good darned thing nobody brought up radians.

Well, yes, especially as red-legs cannot agree on how many millirads are in a circle, which has nothing to do with Radians (2π per circle). And, of course "mils" (thousandths of an inch) are not "mils" for sighting, either (and not millimeters, either).

 

[Rule3]

Strictly speaking, the opposite of the prefix “sub” is “super” (subsonic vs supersonic), but I don’t think that term is useful to the application.

Im pretty sure sub-MOA was a term that began when the ability to shoot smaller than 1 inch @ groups at 100 yards became a more common thing.

I like this one!. My shooting is super MOA!

 

[Buzznrose]

I like this one!. My shooting is super MOA!

LOL! Glad that worked out for ya!

 

[RetiredUSNChief]

Another way of explaining this is as follows:

Accuracy is a mostly a SHOOTER thing. It's the ability of the shooter to sight in and hit the point of aim.

MOA is a mostly a HARDWARE thing. It's what the gun (and ammo) is CAPABLE of.

There is some overlap, of course. Hardware, which includes ammunition, gun, scope, iron sights, cleanliness, etc. can affect accuracy as well as MOA. If the scope is defective/loose, it may be impossible to achieve decent groupings, for example, as well as not be able to accurately hit the point of aim.

But if you assume the ammunition is good, the scope is good, no hurricane winds are gusting across the range, etc., then MOA is defined by the gun itself.

 

[lysanderxiii]

What is sub-MOA?

All rounds inside a diameter less than 1 inch at 100 yards.

Simple.

 

[230RN]

Feh ! Since somebody mentioned radians, the only logical and universal (even on Alpha Centauri VI) expression for an angle is in radians. In which a minute of angle in that very artificial and arbitrary 360° circle scheme is 2.9 X 10e-4 radians (0.000291 rad).

Therefore, I have a sub-2.9 X 10e-4 rad rifle.

Nyah-nyah-nyah, so there, Phphphfffblttt! on you 360°-bound people.

Terry

 

[Hugger-4641]

Feh ! Since somebody mentioned radians, the only logical and universal (even on Alpha Centauri VI) expression for an angle is in radians. In which a minute of angle in that very artificial and arbitrary 360° circle scheme is 2.9 X 10e-4 radians (0.000291 rad).

Therefore, I have a sub-2.9 X 10e-4 rad rifle.

Nyah-nyah-nyah, so there, Phphphfffblttt! on you 360°-bound people.

Terry

You do realize that a mil-rad as applied to shooting is the distance between the legs of an angle as measured around the circumference of another artificial and arbitrary circle?

 

[eyeshot]

EMOA. Embellished _ _ _.

 

[Poper]

All rounds inside a diameter less than 1 inch at 100 yards.

Simple.

Measured center-to-center, that is.
We must be precise, you know!

 

[PWC]

When I started this thread, I knew what MOA meant. My real question was people saying they are shooting MOA, when what they really mean is they are shooting groups < 1" at 100 yd, or the equivelent at other yardage.

MOA is a functional charactistic of the rifle; it can be 8" from the point of aim, and then brought back to the point of aim with rifle work.

 

[Turkeytider]

Another way of explaining this is as follows:

Accuracy is a mostly a SHOOTER thing. It's the ability of the shooter to sight in and hit the point of aim.

MOA is a mostly a HARDWARE thing. It's what the gun (and ammo) is CAPABLE of.

There is some overlap, of course. Hardware, which includes ammunition, gun, scope, iron sights, cleanliness, etc. can affect accuracy as well as MOA. If the scope is defective/loose, it may be impossible to achieve decent groupings, for example, as well as not be able to accurately hit the point of aim.

But if you assume the ammunition is good, the scope is good, no hurricane winds are gusting across the range, etc., then MOA is defined by the gun itself.

I`ve wondered about gun performance and precision ( reproducibility of POI ). Most say that the gun, ammo, scope and environment determine this, TO THE EXCLUSION OF THE SHOOTER. So, as a shooter, I have no impact on precision? If I am not consistent in my shooting form and execution, I cannot believe that that has no impact on group size.

 

[Hugger-4641]

I`ve wondered about gun performance and precision ( reproducibility of POI ). Most say that the gun, ammo, scope and environment determine this, TO THE EXCLUSION OF THE SHOOTER. So, as a shooter, I have no impact on precision? If I am not consistent in my shooting form and execution, I cannot believe that that has no impact on group size.

Of course you have impact on group size. The skill comes by figuring out how to reduce or eliminate your impact.
I have several rifles that I can shoot sub moa groups from bags at 300yds, but no way I can do it offhand. If David Tubb was shooting my rifles, he'd probably shoot 1/4 moa or less with same ammo.

 

[RetiredUSNChief]

I`ve wondered about gun performance and precision ( reproducibility of POI ). Most say that the gun, ammo, scope and environment determine this, TO THE EXCLUSION OF THE SHOOTER. So, as a shooter, I have no impact on precision? If I am not consistent in my shooting form and execution, I cannot believe that that has no impact on group size.

Certainly you have an impact on precision.

However, MOA is really intended to be be an indicator of what the HARDWARE is CAPABLE of doing, not what the shooter is capable of doing.

If you can't hold the rifle steady enough to achieve a tight grouping, that's a shooter problem. However, a rifle fired from a solid bench rest sighted at exactly the same spot every time but cannot produce a tight group is a hardware problem.

As I said in my previous post on this, there is room for some overlap here. However, it's up to the shooter to figure out exactly where the problem lies by some form of process of elimination. Perhaps is the ammunition causing the problem. Perhaps the scope has issues. Perhaps the relationship between the bullet, velocity, and rifling twist rate is the problem. Maybe the crown has a defect. Maybe the bench being shot from isn't as stable as originally thought. Whatever the problem is, it's up to the shooter to figure it out.

If you get a new gun, a pistol for example, and go shooting with it and discover it doesn't group well, what do you do? Blame the gun right off the bat, or do you knuckle down and try to figure out what the problem is? Maybe shoot from a bench rest instead of a standing position? Change ammunition? Have someone else try shooting it? Same thing.

 

[Turkeytider]

I suppose, then, the best way to truly find out what the gun ( equipment) is capable of is to remove the shooter’s influence as much as possible. Lead sled or some other vice like device?

 

[mavracer]

When I started this thread, I knew what MOA meant. My real question was people saying they are shooting MOA, when what they really mean is they are shooting groups < 1" at 100 yd, or the equivelent at other yardage.

We use MOA because the math is easy and it gives the ability to compensate for different distances.
Back in the 70s when I first started shooting the guns and ammo available generally wouldn't shoot 1" at 100 it took work and you about had to reload so MOA was a goal.

MOA is a functional charactistic of the rifle; it can be 8" from the point of aim, and then brought back to the point of aim with rifle work.

If you want to argue semantics the rifle is shooting the exact same you're shifting your point of aim to where it was shooting.

 

[buck460XVR]

For example, as long as everyone understands that 1MOA is about 1" at 100 yards and about 2" at 200 yards, etc. then it doesn't matter whether we talk about groups in inches or MOA.

^^^Yep. Even over six decades ago when I first started shooting firearms(and sub-MOA was a true rarity for most folks) this is how I understood it to mean. This was before I understood ballistics or had even taken a High School Math class. This is one of those arguments, like "which gun for bear?" or "which is better, .45ACP or .45 COLT?" that comes up regularly on these types of forums and is a good example of how subjectivity vs objectivity works. As simple a it is, folks tend to want to complicate it.

 

[jmorris]

MOA is the manufactured, or after market modified accuracy capability of a rifle.

No one is shooting MOA. They are shooting groups with a rifle capable of shooting MOA.

If they are shooting 1" groups, they have adjusted their sights, ammo, position, breathing, etc. to do so.

The minute of angle (MOA) is a unit of angular measurement equal to 1/60th of 1 degree. There are 360 degrees in a circle (think about a compass dial). When more precise measurements are needed, each of those degrees can be divided into 60 minutes of angle (also called minutes of arc). So there are 60 MOA per degree, and a total of 21,600 MOA in a circle (360°x60’).

Being an angular measurement the diameter increases with distance.



Has nothing to do with point of aim relative to point of impact, that’s what the qualitative word accuracy is for. All of your shots (an unknown number unless declared) must make up the diameter to be an “MOA”. If all your bullets fired are in a 1.000” group at 100 yards or greater, that is a sub MOA group (an MOA is 1.047” @ 100 yards). With the right test equipment, it doesn’t matter if the barrel even has sights, how one is breathing or even if the person testing is a good shooter or not as it is a way to quantify how precise a barrel can place bullets relative to one another vs any specific spot.

Even then, it’s not the best way to quantify because “sub MOA”, isn’t descriptive enough for some. Kind of a pointless description of say a benchrest rifle. Where everyone knows any competitive rifle will shoot sub MOA. So they make attempts to further quantify a rifle in that it shoots 1’s, 2’s or 3’s for example, indicating the rifle is capable of shooting groups in the hundred thousandths range indicated, all “sub MOA”.

 

[Nature Boy]

MOA - it’s what your rifle can do all day, if you do your part.

 

[Turkeytider]

MOA - it’s what your rifle can do all day, if you do your part.

I`ve about decided that the majority, if not the entirety, of my shooting issues are summed up in the last five words of Nature Boy`s post.

 

[Ignition Override]

Accurate….torpedoes from submarines?

Or from the old P3 , or modern, quite modified Navy “737” aircraft?

Rifle “Sub MOA”? Well….
Thats my making a Less than 5” group at 100 yards with an aperture sight on my (“HK”) PTR-91.

-//- Do all of you, on a bench/table, also wrap your support hand around onto the buttstock?

RetiredUSNChief: your comments remind me of basic tips from a buddy/former coworker who retired years ago from NAVRES on the Navy Rifle Team.

i knew him for about two years before he quietly mentioned that he set AR records, within whichever category, at 200 and 600 yards.

 

[jmorris]

I`ve about decided that the majority, if not the entirety, of my shooting issues are summed up in the last five words of Nature Boy`s post.

Well there is little need to remain unsure, one can remove themselves quite a bit from the process.



Hard to yank a trigger or move the rifle if you are not touching it.