What is "subMOA" to you?

[LittleLebowski]

This is open ended and I do not think there is a cut and dry answer. Examples of possible answers:


Three shot group at 100 yards, measured center to center with calipers, subtracting the bullet diameter
5 three shot groups at 100 yards measured center to center with calipers, subtracting the bullet diameter, average of all groups
5 ten shot groups at 100 yards measured center to center with calipers, subtracting the bullet diameter, average of all groups
ten first round hits on 1" dots at 100 yards, including the cold bore shot

[LSP552]

I've always considered MOA as measured center to center and wanted less than 1" at 100, 2" at 200, etc. from a bench. For hunting rifles, 3 shot groups are fine. I believe a true MOA rifle is able to keep all of it's 3 shot groups under MOA, not just one every now and then.

[Luke]

A group consisting of nothing outside of 1.047" :)


3 shot groups are for people who need to brag on the Internet. 5 and 10 shot groups are for men.

[SecondsCount]

5 shots at 100 yards measuring less than 1.047" is subMOA in my book. How many times you want to repeat that is up to you but I would say the average of five groups is good.

I did the Arfcom 1 MOA All Day Long challenge last year with my Tikka Sporter 223 and five, 5-shot groups averaged .762 MOA. I was pretty pleased with this since it is a factory rifle, and I was just working up loads when I did it. Largest group was slightly over an inch and smallest was .638. Requirements were to use a bipod and a small bag without support ears which puts a lot more stress on the shooter to perform.

On the other hand when you shoot two groups in a row that look those in this picture, you pretty much know the gun is capable of subMOA, more like sub 1/2 MOA.
http://home.comcast.net/~d_kirk/rifle/223AI/223aigroups2.jpg

I know Molon likes 10 shot groups and I respect that as well.

[Surf]

Measure the largest spread from outside of the grease ring to outside of the grease ring and then subtract caliber size. You can make a close estimate measuring center to center of the largest spread if you want to quickly avoid the math.

Not many who actually mechanically vise / rest the rifle, so the shooter / ammo / optic can be limiting. However if these variables are good to go the weapon variable will be more noticeable, but not exactly a true test of the weapon itself, not too mention other variables that nature dishes up. Having said that, coming up with an average estimation of the MOA that a shooter is capable of producing with a certain rifle and I will generally gauge that by tracking groups over multiple shooting sessions. For a good or consistent shooter, I would like to come up with stats for at least 20 groups of at least 5 rounds per group which includes the cold bore / cold shooter. I understand the concept for larger groups in regards to variables and that is OK also, but IMO not a necessity if you simply track results over time which I think should be done anyway.

In no way can a shooter take one single sample of their best ever 3 round group and post a picture and claim that as fact. Unfortunately we see that happen all the time. I wouldn't even accept a single 3 round group out of a mechanical vise / rest and let that one group claim stand as a weapons capability. Larger sample sizes are needed.

[TGS]

Good topic.

Partly, I think it depends on the purpose of the rifle. If you need to maintain sub-MOA for a semi-auto DMR, recce, 3 gun or benchrest rifle, then I think 10 shot groups are more appropriate in determining the weapon's capability.

If you're using a light barreled bolt action hunting rifle, then there's not much purpose in chasing 10 shot groups. Your gun likely only holds 3-5 rounds as it is, and the majority of hunters are not going to use more than 1 shot. Shooting some 3 shot groups under differing weather conditions is ample at determining the capability of this weapon in its intended role.

In this case, I actually think the opposite of some of you.....chasing 10 round groups is for people who want to brag on the internet, not the other way around.

What about muzzle loaders? At one point I had an obnoxiously accurate .50 cal that would print 3 shot clover leafs any day at 100 yards. Why should I care about 5-10 shot groups? It's a fucking muzzle-loader. You couldn't even load more than 3 shots between cleanings. But somehow using 3 shot groups isn't appropriate in determining its accuracy? Are you high?

[UNK]

Too be able to place called shots inside of a 1" circle per 100 yards. dia of circle x 100 yard increments.
I don't care if its one shot cold bore or groups or multiple individual shots on multi 1 inch circles. If you can consistently place your hit inside the circle its sub moa.

[45dotACP]

If I shoot 5 five shot groups within an inch at 100 yards, I'm pretty comfortable slapping the "one moa at 100 yards with this load" label on a rifle. A thought....Just because the load you shot through the rifle is one inch at a hundred doesn't mean it'll hold true at longer distances.

Sent from my VS876 using Tapatalk

[JHC]

If I ever see ONE five shot group 1" center to center, I call that rifle MOA forever! ;)

I really thought that's all there was to it until seeing discussions like this just in the last few + years. Molon here or elsewhere may have been the first to post things that made me say waaaaaaaaaaat?

[rob_s]

I was shown the idea of shooting a separate dot for each round several years ago after some friends returned from Rifles Only. I really like the idea of putting them, 1" dots on a page and if you're >50% in each dot then you're good.

[dbateman]

5 shots under one moa at any given range.

[LittleLebowski]

I was shown the idea of shooting a separate dot for each round several years ago after some friends returned from Rifles Only. I really like the idea of putting them, 1" dots on a page and if you're >50% in each dot then you're good.

That's where I got the idea.

[MDS]

A Bearded Tier One taught me the 1-shoot group technique, measuring the spread at the grease ring. This yielded the best improvement in my shooting since I got my timer customized.

But if I ever choose to do 5- or 10-shot groups, what's the logic behind using a separate dot/target for each one?

[LittleLebowski]

But if I ever choose to do 5- or 10-shot groups, what's the logic behind using a separate dot/target for each one?

I think it is just a different way to do things. One can argue that it is slightly harder because you have to adjust your weapon for each target (minutely to be sure), I suppose.

For me, it's a great confidence builder as opposed to simply hammering at one POA with 5-10 rounds.

[LittleLebowski]

For a good or consistent shooter, I would like to come up with stats for at least 20 groups of at least 5 rounds per group which includes the cold bore / cold shooter.

That would wear me out with regards to shooter fatigue and the same for many others, I would bet.

[UNK]

That's the point of three hundred yard qualification rapid fire dog target. Change magazines in the middle of the string reacquire stock placement stock weld and sight picture. Once you are locked in its a lot easier to maintain than to get.


I think it is just a different way to do things. One can argue that it is slightly harder because you have to adjust your weapon for each target (minutely to be sure), I suppose.

For me, it's a great confidence builder as opposed to simply hammering at one POA with 5-10 rounds.

[JHC]

re the MOA measurement of shots to different 1" dots . . .

I figured it had martial or hunting reasoning. Each shot in the field is a single shot. No groups for score. So how close to that 1 MOA each discrete shot can be made indicates MOA on a field target be they game or enemy. Just spit ballin'

[LittleLebowski]

re the MOA measurement of shots to different 1" dots . . .

I figured it had martial or hunting reasoning. Each shot in the field is a single shot. No groups for score. So how close to that 1 MOA each discrete shot can be made indicates MOA on a field target be they game or enemy. Just spit ballin'

To me, it's a practical test as opposed to actually measuring a group size with calipers. Simply hit each dot.

With full credit to Frank Galli and SnipersHide, here are the aforementioned dot drills (PDFs)

SnipersHide Dot Drill (https://dl.dropboxusercontent.com/u/7231062/SH%20Dot%20Drill%20.pdf)

SnipersHide Advanced Dot Drill (https://dl.dropboxusercontent.com/u/7231062/Advanced%20Dot%20Drill.pdf)

[LittleLebowski]

Well done, well done. I love ARF's "1 MOA All Day Long" challenge.


5 shots at 100 yards measuring less than 1.047" is subMOA in my book. How many times you want to repeat that is up to you but I would say the average of five groups is good.

I did the Arfcom 1 MOA All Day Long challenge last year with my Tikka Sporter 223 and five, 5-shot groups averaged .762 MOA. I was pretty pleased with this since it is a factory rifle, and I was just working up loads when I did it. Largest group was slightly over an inch and smallest was .638. Requirements were to use a bipod and a small bag without support ears which puts a lot more stress on the shooter to perform.

On the other hand when you shoot two groups in a row that look those in this picture, you pretty much know the gun is capable of subMOA, more like sub 1/2 MOA.
http://home.comcast.net/~d_kirk/rifle/223AI/223aigroups2.jpg

I know Molon likes 10 shot groups and I respect that as well.

[rob_s]

I think it is just a different way to do things. One can argue that it is slightly harder because you have to adjust your weapon for each target (minutely to be sure), I suppose.

For me, it's a great confidence builder as opposed to simply hammering at one POA with 5-10 rounds.

All of this.

To me, the question is not "how many rounds can I put into a single POA?" but "how close to a single POA can I come with a single round?" A minute (get it, "minute"?) distinction to be sure, but one that just resonates in my brain for whatever reason.

[ST911]

I'm not a precision rifle guy, but I've been dipping my toe in that water recently. I shot these targets, below. Where this thread is concerned, I found that keeping sub-MOA with 3 round groups wasn't too difficult. My first round cold-bore shot was true when I started out for the day. I think those tell me something about the gun. The value of the 10rd groups were what they told me about where I am as a shooter.

I like the dot targets in the link. I'll try the aggregated shot group next outing with this gun.

16/11 Stealth. Optic is a Leupold VX-R Patrol 3-9x40. Prone at 100yd, rested across a downed tree.

http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/lt.jpg

These are three round groups shot while playing with my turret adjustments, BHA 55 FMJ. The L/R groups are at the edge of the paper, but the U/D groups are clear and can be measured. Bottom group without info is .65"/.62MOA.

http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/3rd%20grps%20TgtGfx.jpg

55gr FMJ 10rd group
http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/BHA%2055%20FMJ%20TgtGfx.jpg

Mk262 10rd group
http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/Mk%20262%20TgtGfx.jpg

5.56 62gr 10rd TSX group
http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/62%20TSX%20556%20TgtGfx.jpg

When I pull the two worst rounds off, the remaining 8 are a nice cluster and come in at ~1.3".
http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/62%20TSX%20556%208rd%20TgtGfx.jpg

[johnson]

To me it means multiple 5 round groups or a single 10 round group measured <1" CTC. And like Surf mentioned, it's a good idea to keep a record of group sizes over multiple sessions to get an average.

There's also the question of mechanical accuracy vs shooter accuracy. What you can do is clamp the rifle and shoot your 5/10 shot group(s) to get a baseline to know what the rifle is capable of. Then remove all that and just shoot with a sling and use your magazine for support (ala Appleseed) so you know what factors you are bringing to the group size.

In this video, John McQuay shoots 10 shot groups using a different method. Dry fire 5 times, shoots one round, then gets up and walks around to break cheek weld and concentration. Repeat 10 times.


https://www.youtube.com/watch?v=mpf5v41xt0E

[rwa]

I usually use IPH instead of MOA. It's easier to just ditch the .047". I use an aggregate of five groups consisting of five shots per group. I rarely shoot all five strings on the same day. It's important to me to have gear that shoots under a wide variety of environmental conditions ranging from temperatures of -10 F to +95 F. I measure center to center with "On Target software. The rifle also needs to hold sub 1 inch per hundred yards out to the maximum distance that I would normally shoot with the rifle. For sporter weight rifles that's 600 yards. For varmint/precision rifles I regularly shoot out to 800 yards. At 1000 yards the environmental conditions will whip my ass long before I can churn out a handful of 10 inch groups.

[Alpha Sierra]

Given my background as a highpower rifle competitor, MOA to me is a rifle that will hold the X ring for an entire prone 20 round sting, absent environmental issues like any significant wind.

It take a good hold and a scope, but it's quite doable with any NM AR15 built with a good (Shilen, Krieger, Obermeyer, Satern) barrel

[Alpha Sierra]

All of this.

To me, the question is not "how many rounds can I put into a single POA?" but "how close to a single POA can I come with a single round?" A minute (get it, "minute"?) distinction to be sure, but one that just resonates in my brain for whatever reason.

Those are two different questions that measure different aspects of shooter skill and rifle accuracy

Both are valid tests, for different reasons.

[dbateman]

But if I ever choose to do 5- or 10-shot groups, what's the logic behind using a separate dot/target for each one?

Shooting groups and shooting dot drills are used for different things.

Dot drills aren't so much about the rifles accuracy it's about the shooters ability to build positions.
A dot drill isn't just about hitting the dot there is a lot more to it.

[rob_s]

Those are two different questions that measure different aspects of shooter skill and rifle accuracy

Both are valid tests, for different reasons.

Yes.

One matters to me, one doesn't.

[Unobtanium]

This is open ended and I do not think there is a cut and dry answer. Examples of possible answers:


Three shot group at 100 yards, measured center to center with calipers, subtracting the bullet diameter
5 three shot groups at 100 yards measured center to center with calipers, subtracting the bullet diameter, average of all groups
5 ten shot groups at 100 yards measured center to center with calipers, subtracting the bullet diameter, average of all groups
ten first round hits on 1" dots at 100 yards, including the cold bore shot


The last. Using that standard, with a red-dot and magnifier, my Daniel Defense is a sub 2 MOA gun using bonded softpoint 5.56 ammo. I know many people who would consider it "SUB MOA" based on other criteria, but I think that's delusional.

[Unobtanium]

I'm not a precision rifle guy, but I've been dipping my toe in that water recently. I shot these targets, below. Where this thread is concerned, I found that keeping sub-MOA with 3 round groups wasn't too difficult. My first round cold-bore shot was true when I started out for the day. I think those tell me something about the gun. The value of the 10rd groups were what they told me about where I am as a shooter.

I like the dot targets in the link. I'll try the aggregated shot group next outing with this gun.

16/11 Stealth. Optic is a Leupold VX-R Patrol 3-9x40. Prone at 100yd, rested across a downed tree.

http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/lt.jpg

These are three round groups shot while playing with my turret adjustments, BHA 55 FMJ. The L/R groups are at the edge of the paper, but the U/D groups are clear and can be measured. Bottom group without info is .65"/.62MOA.

http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/3rd%20grps%20TgtGfx.jpg

55gr FMJ 10rd group
http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/BHA%2055%20FMJ%20TgtGfx.jpg

Mk262 10rd group
http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/Mk%20262%20TgtGfx.jpg

5.56 62gr 10rd TSX group
http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/62%20TSX%20556%20TgtGfx.jpg

When I pull the two worst rounds off, the remaining 8 are a nice cluster and come in at ~1.3".
http://i76.photobucket.com/albums/j18/Skintop911/LT%20Stealth/62%20TSX%20556%208rd%20TgtGfx.jpg

That's what I got out of 5.56 Black hills 62gr TSX with my daniel defense M4 and red-dot/magnifier as well. Roughly 2.5 MOA with a couple of fliers included in every group. It's not the most consistent of loads. I don't shoot off of bags or anything, just use the magazine as a monopod and sit at the bench (public range) when doing accuracy comparison. However, the last 3 ten-shot groups I had fired were 1.9,2.0, and 2.1 MOA, as I recall, using Ranger Bonded, and there were no fliers, so I refuse to take the blame for the TSX's performance, as EVERY group showed either stringing, or a flier, with it.

http://i60.tinypic.com/2cxz5li.jpg
http://i59.tinypic.com/zjursj.jpg
http://i57.tinypic.com/30t12s4.jpg

[Failure2Stop]

I posted this a while ago on M4:

Ask someone how "accurate" they want their rifle to be, and generally you will hear a response of something about "1 MOA", "Sub-MOA", or "nothing over 2 MOA", depending on application.

First things first: Accuracy vs Precision

There is a difference between "accuracy" and the size of a group (commonly called "precision").
For the moment, let's stick with the conventional lingo for this part.
In the simplest perspective, accuracy is simply hitting a target of a specified size.
Precision (in this context) refers to group size (more on that later).
This pic does a decent job of simplifying the concept:
http://cdn.antarcticglaciers.org/wp-content/uploads/2013/11/precision_accuracy.png
So, you can be accurate, but not precise, and precise but not accurate.

Now, to get in the weeds about this, linking group size to precision is less descriptive than simply discussing "dispersion", that is, the distance between each point of impact. So, for the rest of this, I will be mostly discussing dispersion.

What is 1 MOA?

In the simplest terms possible, 1 Minute of Angle (MOA) is 1.047" at 100 yards, measured from the end of the muzzle.
This distance increases in direct proportion to distance: 2.094" at 200 yards, 10.47" at 1,000 yards, 3.42" at 327 yards, etc.
We, being lazy, tend to round this number to 1" per every 100 yards of distance. Frankly, it doesn't matter a whole lot, but it does let the guy that shoots a 1" group at 100 truthfully say that he shot a sub-MOA group, which makes people feel good about themselves.
If you want to know more about Minute of Angle (Minute of Arc, semi-technically), the world of Google is a click away.
Be warned: it's super boring, and won't help you shoot any better.

What is a 1 MOA group?

Well, the first question that you didn't ask is: by what measuring convention?
Your reply to the question you didn't ask is most likely something about the distance between the two furthest away shots in a group.
That is the most common approach to measuring groups, and is called "Extreme Spread".
(Note: that is also the nickname of my high-school best friend's sister)

ES is good in the aspect that it is very easy to measure.
ES is bad in that it doesn't really tell you much about the group.
How so?

Let's look at these two groups I happened to have readily available:
http://i296.photobucket.com/albums/mm174/Fail2Stop/cc77c239-5ce0-4271-8fac-f0202010127c.jpghttp://i296.photobucket.com/albums/mm174/Fail2Stop/39758f07-a357-491c-bc52-a9f97758054a.jpg
Which is the best group?

Most would consider the one on the left to be the "better" group, and would attribute the high shot to an ammunition or shooter issue, which it very well may be, but they will then discard that shot from the data set, which is not good at all. There is no point in gathering data and then throwing out the bits that you don't like. Now, if the shooter called the shot as off, BEFORE SEEING THE IMPACT, then it isn't such a problem to dismiss the shot. That said, something that far out would be readily apparent to the shooter if at magnification.

Anyway, if you are using ES as your sole data point for group comparison, the right side group would be better, at around 0.95 MOA, with the left group at around 1.55 MOA, even though 4 of the rounds are in a .5 MOA cluster.

Is there a better way?
One could use Average Mean Radius (aka Average to Center) as a method to discuss group sizes.
The concept is that instead of talking about the extremes of the group, we discuss the average distance from the center of the group to the individual holes. AMR minimizes anomalies, but can be misleading when talking to someone that is thinking in ES.
Molon has written up the "hows" and "whys" of this pretty well, and of course, Google is your friend for learning more about it.
Short story: if you get the "On Target" software, you can do this fairly easily at home, but you need a computer and some savviness to do it.
ES is pretty easily done with just a ruler.
So, is AMR better than ES?
No, it's just different. But better. Kind of.

Here is what On Target will give you:
http://i296.photobucket.com/albums/mm174/Fail2Stop/ACCEX1OT.png
Max is ES, ATC is AMR

Moving on.

So what criteria makes for a "1 MOA" gun?
Lots of dudes will go out to the range, shoot a bunch of groups, find the one that looks the smallest, measure it, and declare that they have a "sub-MOA" gun.
Of course, they disregard all of the 1.5-2.5 MOA groups that they shot before and after that group. While they very well may have a 1 MOA gun/ammo combination, they do not have the data to support that claim.

If they have a rifle that shoots 9 groups that measure 0.9", but 1 of 1.9", is that a "Minute Gun"? Sure, it might average 1 MOA, but is that really in accord with the impression given when one claims that they have a 1 MOA rifle?

Groups Shift.

Yup, they do. Get over it.
Where a bullet will go when fired through a cold, clean bore will be different than where shot 529 will go.
How much the Point of Impact (POI) will shift will be greatly linked to the condition of the bore and temperature of the barrel.
Steel expands when heated and contracts when cooled. Shooting faster will push more heat into the barrel steel.
Copper and fouling will change how the bullet interacts with the bore, and how much the jacket is deformed.
Every shot taken through a barrel is unique.

I tend to prefer barrels and complete systems that show the least amount of group to group shift after fouling.
Kinda showing my hand here, but I would rather have a 1.5 MOA gun with 0.5 inches of shift than a 0.5 MOA gun with 1.5 inches of shift.
I'll let you ruminate on that before addressing it directly.

How much shift happens?
With one particular adopted Army sniper system, the specified allowable shift is 1.1" at 100 yards over 4 groups.

So what?
The only way to know what the gun actually shoots is to compare numerous groups.
The single most important aspect is the center of the group, and where your statistical center lies in relation to your desired point of impact at a stated distance.
Why?
Because each group is unique, and represents a very small data point when it comes to really knowing what the gun shoots. That is, until it is time to use that rifle in the defense of life.
What the individual group sizes are is almost irrelevant. Any of those individual groups could have any of the others' ES or AMR, and those numbers mean nothing practically if they don't go where you need them.

How many rounds to shoot in a group?
There are pros and cons to 5 and 10 round groups.
3 round groups tell you pretty much nothing useful unless you overlay around 10 of them, and frankly are too limited to really give a good indication of group center, which means that it gets harder to accurately track group shift from POA.

10 round groups are good, in fact I used to prefer them, and still do for non-precision low recoil guns. They get a little tiresome after the first 3 or 4, and can start showing heat effect more than baseline precision and shift. Shooter error with 10-round groups usually isn't a big deal right out of the gate, but when you get into the 200 round area shooter fatigue becomes more of a thing.

For dispersion and group-center shift, I prefer 5-round groups. A single 5-round group on its own is indeed a data point, but that data needs to be populated with several (at least 4) groups to accurately indicate anything usable.

This comes around to zeroing.
After my initial zero, I won't touch the turrets until I have at least 4 groups from which to determine actual group center.
If the group center isn't consistent with regard to point of aim, I want to check heat, and will generally shoot 4X 5-round groups, with enough time between strings to allow the barrel to cool.
If the group centers become more consistent, I do a heat work-up, shooting 40 to 50 rounds in 5-round groups with only enough time between groups to ensure good natural point of aim and correct position/NPA.
If the group to group dispersion does not improve, I at least know that the issue is probably something other than heat.

When it comes to data collection, I am more interested in group centers in relation to the POA than I am in individual group size. After shooting the gun for a while, I know what the groups should look like, and anything weird (large) gets noted

So what is a 1 MOA gun?
A true 1 MOA rifle would be capable of consistently placing the center of every round fired within 0.5" of the intended point of impact at 100 yards, for multiple groups, with the same POA for all groups, with the only changes to POI being made by environmental factors.

Like I have said before: there aren't too many of those rifles in the world.

In the end, I don't really care about claiming to have "sub-minute" guns. I expect on-demand performance.
A 1.5" gun (no group size over 1.5" ES, or no shots further from the center of any individual group than 1") with group to group shift of less than 0.5" is an exceptional performer, and frankly, of higher performance than most "sniper" rifles. This combination ensures that as long as I do my job, I will hit a 2" circle at 100 yards every...single...time.
This translates to a 12" target at 600 yards. Think of 100% success on a chest plate at 600.

Lets talk about that "0.5 MOA" gun with 1.5 MOA of shift:

It encourages a shooter to "chase zero". In this situation, the shooter puts out a nice group, and assumes that he did everything right, and therefore adjusts the optic to bring the group to the center of the target. He/she then shoots another group, and sees another good group, but outside the center of the target. So what do they do? Yup, crank away on the turrets again. Had that shooter simply fired 4 or more groups of 5 rounds and compared those group centers to the point of aim, he would be able to determine if the aiming device actually needed to be adjusted (group center average was not within 60% of a single click value) or if he is simply seeing the inherent group shift.

Most critically, is that it becomes very easy to overestimate performance potential, and wind up taking shots that the gun doesn't fully support. Shooter takes gun to range, shoots a bunch of the above .5 MOA groups and by chance happens to get his final group exactly where it's supposed to be. When it's time to take that .5 MOA shot, the group shift puts the projectile 1.5 MOA away from the intended impact point. Successive shots go around the same place, leading the shooter to adjust the optic/point of aim to achieve hits. Data for drop/wind (and truing) gets entered under the assumption that those variables, rather than inherent group shift, are responsible for the needed adjustment, which throws off the entire data set. This issue will continue to affect the data set (during following live-fire sessions) until sufficient data is accumulated and scrutinized with a careful and analytical eye.

All because you shot a 0.5" group that one time...

[nycnoob]

> What is 1 MOA?
>
> In the simplest terms possible, 1 Minute of Angle (MOA)
> is 1.047" at 100 yards, measured from the end of the muzzle.


I would like to ask about this statement as I have given it much
thought and it just does not make sense to me (though I heard Sean say
something similar a while back so it must be industry standard).

1) When measuring the precision of a rifle in MOA then measuring
distance from the muzzle appears to be appropriate (we measure the
spread of shots as they leave the rifle). This is particularly true
for bench resting the gun.


2) However if we are trying to measure "my moa" with a particular
rifle, and a particular position (standing, kneeling, prone) I do not
think that the muzzle is the place to measure the distance. I have to
be behind the firing line and I would assume that this is a better
place for measuring my own accuracy (especially if you wish to compare
how I shoot a long barreled an short barreled gun).


3) However red dot sights are also measured in MOA. Clearly this MOA
does not mean from the muzzle so perhaps it means distance from the
eye to the target. I believe here we are measuring the apparent size
(scale invariant) of the image on my retina.


4) Similarly many people use scaled targets to shoot. A 4 MOA target
at 25 yards is probably not measured from the muzzle. These also are
apparently measured from the eye.


5) The only way I can understand all these facts together is to think
of the shooting as a whole system which includes: me, the rifle, the
optic, the target. And for the system, the firing line appears to be
the correct place to measure from not the muzzle and not the eye. I am
sure that the practical difference is minuscule but I can not
understand this the other way.

[SecondsCount]

MOA is an angular measurement. A minute at 100 yards is 1.047" and at 400 yards is 4 times that. At 50 yards, 1 MOA is 0.5235".

A red dot is also measured in MOA as in a 2 MOA dot will look like 2" in diameter at 100 yards and 8" in diameter on a 400 yard target. If you are shooting at a 3" diameter target at 300 yards, it will be hard to see because the 2 MOA dot will look like it is 6" in diameter and will prevent you from making out the outer edges of the target.

As far as targets go, take one that is a human silhouette for example. At 21 feet it looks like a normal sized human being but place it at 10 times the distance and it starts to look smaller. To create that affect when training at shorter distances, reduced size targets are created to make the short range distance look like a long range scenario.

As far as the whole system is concerned it goes both ways. If I take a M&P9, strap it in a ransom rest, and shoot a 5" group at 25 yards, the gun could be considered a 20 MOA gun because the human factor has been removed. If I take my HK and shoot a 5" group at that distance, you know that it is most likely the ammo or me that is at fault for the gun being considered a 20 MOA pistol. This is because HK has a good reputation as being an accurate pistol and the M&P9, not so much.

This is why the MOA challenge on Arfcom was devised. It measured not only the precision of the rifle but also the ammo used, and the person behind the trigger. It also weeded out a lot of supposedly awesome low cost rifles that were "as good as" the high priced rifles.

[Odin Bravo One]

SubMOA means sub-minute of asshole. Meaning any rounds I fire are well within the effective target zone of an asshole who needs to be shot.

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Clear concise well articulated. Thanks for taking the time to put that togather.


I posted this a while ago on M4:

Ask someone how "accurate" they want their rifle to be, and generally you will hear a response of something about "1 MOA", "Sub-MOA", or "nothing over 2 MOA", depending on application.

First things first: Accuracy vs Precision

There is a difference between "accuracy" and the size of a group (commonly called "precision").
For the moment, let's stick with the conventional lingo for this part.
In the simplest perspective, accuracy is simply hitting a target of a specified size.
Precision (in this context) refers to group size (more on that later).
This pic does a decent job of simplifying the concept:
http://cdn.antarcticglaciers.org/wp-content/uploads/2013/11/precision_accuracy.png
So, you can be accurate, but not precise, and precise but not accurate.

Now, to get in the weeds about this, linking group size to precision is less descriptive than simply discussing "dispersion", that is, the distance between each point of impact. So, for the rest of this, I will be mostly discussing dispersion.

What is 1 MOA?

In the simplest terms possible, 1 Minute of Angle (MOA) is 1.047" at 100 yards, measured from the end of the muzzle.
This distance increases in direct proportion to distance: 2.094" at 200 yards, 10.47" at 1,000 yards, 3.42" at 327 yards, etc.
We, being lazy, tend to round this number to 1" per every 100 yards of distance. Frankly, it doesn't matter a whole lot, but it does let the guy that shoots a 1" group at 100 truthfully say that he shot a sub-MOA group, which makes people feel good about themselves.
If you want to know more about Minute of Angle (Minute of Arc, semi-technically), the world of Google is a click away.
Be warned: it's super boring, and won't help you shoot any better.

What is a 1 MOA group?

Well, the first question that you didn't ask is: by what measuring convention?
Your reply to the question you didn't ask is most likely something about the distance between the two furthest away shots in a group.
That is the most common approach to measuring groups, and is called "Extreme Spread".
(Note: that is also the nickname of my high-school best friend's sister)

ES is good in the aspect that it is very easy to measure.
ES is bad in that it doesn't really tell you much about the group.
How so?

Let's look at these two groups I happened to have readily available:
http://i296.photobucket.com/albums/mm174/Fail2Stop/cc77c239-5ce0-4271-8fac-f0202010127c.jpghttp://i296.photobucket.com/albums/mm174/Fail2Stop/39758f07-a357-491c-bc52-a9f97758054a.jpg
Which is the best group?

Most would consider the one on the left to be the "better" group, and would attribute the high shot to an ammunition or shooter issue, which it very well may be, but they will then discard that shot from the data set, which is not good at all. There is no point in gathering data and then throwing out the bits that you don't like. Now, if the shooter called the shot as off, BEFORE SEEING THE IMPACT, then it isn't such a problem to dismiss the shot. That said, something that far out would be readily apparent to the shooter if at magnification.

Anyway, if you are using ES as your sole data point for group comparison, the right side group would be better, at around 0.95 MOA, with the left group at around 1.55 MOA, even though 4 of the rounds are in a .5 MOA cluster.

Is there a better way?
One could use Average Mean Radius (aka Average to Center) as a method to discuss group sizes.
The concept is that instead of talking about the extremes of the group, we discuss the average distance from the center of the group to the individual holes. AMR minimizes anomalies, but can be misleading when talking to someone that is thinking in ES.
Molon has written up the "hows" and "whys" of this pretty well, and of course, Google is your friend for learning more about it.
Short story: if you get the "On Target" software, you can do this fairly easily at home, but you need a computer and some savviness to do it.
ES is pretty easily done with just a ruler.
So, is AMR better than ES?
No, it's just different. But better. Kind of.

Here is what On Target will give you:
http://i296.photobucket.com/albums/mm174/Fail2Stop/ACCEX1OT.png
Max is ES, ATC is AMR

Moving on.

So what criteria makes for a "1 MOA" gun?
Lots of dudes will go out to the range, shoot a bunch of groups, find the one that looks the smallest, measure it, and declare that they have a "sub-MOA" gun.
Of course, they disregard all of the 1.5-2.5 MOA groups that they shot before and after that group. While they very well may have a 1 MOA gun/ammo combination, they do not have the data to support that claim.

If they have a rifle that shoots 9 groups that measure 0.9", but 1 of 1.9", is that a "Minute Gun"? Sure, it might average 1 MOA, but is that really in accord with the impression given when one claims that they have a 1 MOA rifle?

Groups Shift.

Yup, they do. Get over it.
Where a bullet will go when fired through a cold, clean bore will be different than where shot 529 will go.
How much the Point of Impact (POI) will shift will be greatly linked to the condition of the bore and temperature of the barrel.
Steel expands when heated and contracts when cooled. Shooting faster will push more heat into the barrel steel.
Copper and fouling will change how the bullet interacts with the bore, and how much the jacket is deformed.
Every shot taken through a barrel is unique.

I tend to prefer barrels and complete systems that show the least amount of group to group shift after fouling.
Kinda showing my hand here, but I would rather have a 1.5 MOA gun with 0.5 inches of shift than a 0.5 MOA gun with 1.5 inches of shift.
I'll let you ruminate on that before addressing it directly.

How much shift happens?
With one particular adopted Army sniper system, the specified allowable shift is 1.1" at 100 yards over 4 groups.

So what?
The only way to know what the gun actually shoots is to compare numerous groups.
The single most important aspect is the center of the group, and where your statistical center lies in relation to your desired point of impact at a stated distance.
Why?
Because each group is unique, and represents a very small data point when it comes to really knowing what the gun shoots. That is, until it is time to use that rifle in the defense of life.
What the individual group sizes are is almost irrelevant. Any of those individual groups could have any of the others' ES or AMR, and those numbers mean nothing practically if they don't go where you need them.

How many rounds to shoot in a group?
There are pros and cons to 5 and 10 round groups.
3 round groups tell you pretty much nothing useful unless you overlay around 10 of them, and frankly are too limited to really give a good indication of group center, which means that it gets harder to accurately track group shift from POA.

10 round groups are good, in fact I used to prefer them, and still do for non-precision low recoil guns. They get a little tiresome after the first 3 or 4, and can start showing heat effect more than baseline precision and shift. Shooter error with 10-round groups usually isn't a big deal right out of the gate, but when you get into the 200 round area shooter fatigue becomes more of a thing.

For dispersion and group-center shift, I prefer 5-round groups. A single 5-round group on its own is indeed a data point, but that data needs to be populated with several (at least 4) groups to accurately indicate anything usable.

This comes around to zeroing.
After my initial zero, I won't touch the turrets until I have at least 4 groups from which to determine actual group center.
If the group center isn't consistent with regard to point of aim, I want to check heat, and will generally shoot 4X 5-round groups, with enough time between strings to allow the barrel to cool.
If the group centers become more consistent, I do a heat work-up, shooting 40 to 50 rounds in 5-round groups with only enough time between groups to ensure good natural point of aim and correct position/NPA.
If the group to group dispersion does not improve, I at least know that the issue is probably something other than heat.

When it comes to data collection, I am more interested in group centers in relation to the POA than I am in individual group size. After shooting the gun for a while, I know what the groups should look like, and anything weird (large) gets noted

So what is a 1 MOA gun?
A true 1 MOA rifle would be capable of consistently placing the center of every round fired within 0.5" of the intended point of impact at 100 yards, for multiple groups, with the same POA for all groups, with the only changes to POI being made by environmental factors.

Like I have said before: there aren't too many of those rifles in the world.

In the end, I don't really care about claiming to have "sub-minute" guns. I expect on-demand performance.
A 1.5" gun (no group size over 1.5" ES, or no shots further from the center of any individual group than 1") with group to group shift of less than 0.5" is an exceptional performer, and frankly, of higher performance than most "sniper" rifles. This combination ensures that as long as I do my job, I will hit a 2" circle at 100 yards every...single...time.
This translates to a 12" target at 600 yards. Think of 100% success on a chest plate at 600.

Lets talk about that "0.5 MOA" gun with 1.5 MOA of shift:

It encourages a shooter to "chase zero". In this situation, the shooter puts out a nice group, and assumes that he did everything right, and therefore adjusts the optic to bring the group to the center of the target. He/she then shoots another group, and sees another good group, but outside the center of the target. So what do they do? Yup, crank away on the turrets again. Had that shooter simply fired 4 or more groups of 5 rounds and compared those group centers to the point of aim, he would be able to determine if the aiming device actually needed to be adjusted (group center average was not within 60% of a single click value) or if he is simply seeing the inherent group shift.

Most critically, is that it becomes very easy to overestimate performance potential, and wind up taking shots that the gun doesn't fully support. Shooter takes gun to range, shoots a bunch of the above .5 MOA groups and by chance happens to get his final group exactly where it's supposed to be. When it's time to take that .5 MOA shot, the group shift puts the projectile 1.5 MOA away from the intended impact point. Successive shots go around the same place, leading the shooter to adjust the optic/point of aim to achieve hits. Data for drop/wind (and truing) gets entered under the assumption that those variables, rather than inherent group shift, are responsible for the needed adjustment, which throws off the entire data set. This issue will continue to affect the data set (during following live-fire sessions) until sufficient data is accumulated and scrutinized with a careful and analytical eye.

All because you shot a 0.5" group that one time...

[LittleLebowski]

Failure2Stop's excellent post has been added to our Reference Section (https://pistol-forum.com/forumdisplay.php?24-Reference-Section).

[GRV]

SubMOA means sub-minute of asshole. Meaning any rounds I fire are well within the effective target zone of an asshole who needs to be shot.

Sub-minute-of-asshole, huh? No entry wound... Gives a whole new meaning to the one-hole drill.