Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Posted: 7/21/2010 10:57:54 AM EDT
This comes from a discussion on another gun forum.... I came to realize that we as a shooting community have adopted the phrase MOA as a term to describe accuracy/linear distance/angular distance.

I think we are doing it wrong... but simply stick with it for the sake of not getting into a semantics battle to understand eachother.

So here's my understanding.

MOA = minute of angle/minute of arc.

1 MOA is the angular measurement of 1/60th of 1 degree on a 360* circle.

It is just so happens to be that at 100yds the angular measurement of 1 MOA is 1.047"... for simplicity we simply round it down to 1" as the difference is less than 5%

So... when we look at our scope... it says on the top... 1/4" @ 100yds or 1/4MOA @ 100yds... My opinion is that the first labelling of (1/4" @ 100yds) is inaccurate and simply done not to confuse people... and here's why.

MOA is the angular distance between the infinitely long line drawn through the crosshairs of the scope and the infinintely long line drawn through the center of the barrel...

When we adjust our scopes we are changing the ANGLE of those lines... which intern would change the angular distance between them at said distance...
If you do "one click" on a 1/4MOA adjustment scope you have changed the angular distance by 1/4MOA at 100yds of the arc of the angle... this is correct.

If one says you are changing the angular distance by 1/4" at 100yds you would be wrong as you are using a linear measurment to describe a angular distance.. because linear distance doesn't change at different yardage... 1/4" at 100yds is 1/4" at 1000yds... 1MOA at 100yds doesn't have the same distance as 1MOA at 1000yds.

Same thing with targets...

One can say that their gun is a "1 MOA gun" this means that the extreme spead of the bullet impacts will be at or within a 1MOA angle at any distances... this is mathematically correct.

To say that one has a 1MOA group at 100yds which equals 1" is wrong...here is why...

You are saying that the LINEAR distance between your extreme spread of bullet holes is 1"... then you are saying that it is also 1MOA... this is wrong as you are expressing a LINEAR distance on paper using a ANGULAR measurement unit.

Here's a picture of what I mean...



Unless the target was concave to the same concavity of the arc of 1/60th of 1* at 100yds.... the length would never be 1MOA.

I know I am way over thinking it... but what do you guys think? I was just thinking about it and realized that we are using the mathematical terms wrong/not understanding why(I hate being in engineering)

Mike.
Link Posted: 7/21/2010 11:05:34 AM EDT
*** news flash...I actually found something interesting..

Inch per hundred yards (IPHY) is what is also called "shooter's MOA" which allows for the relation of linear and angular distances since in that application it makes sense... where as on a grand scale in other mathematical applications it wouldn't make sense.

Mike.
Link Posted: 7/21/2010 12:15:15 PM EDT
[Last Edit: 7/21/2010 12:21:41 PM EDT by Andr0id]
Geometrically you are correct, but since you have a Isosceles triangle with two 100 yd sides and an 1 inch side, the actual difference between the length of the 1 minute of arc section and the 1 inch of the triangle are very close to zero.

To do the math, 60 x 360 x 1 inch = 21600 inches

and

100 x 36 x 2 * pi = 22618 inches

so the difference is about .05%

Link Posted: 7/21/2010 6:20:25 PM EDT
Your diagram = Fail

Think about it some more and get back to us.
Link Posted: 7/21/2010 11:57:43 PM EDT
Originally Posted By rarelyaccurate:
Your diagram = Fail

Think about it some more and get back to us.


Ummm.. do explain your reasoning.

Mike.
Link Posted: 7/22/2010 8:38:56 PM EDT
You are WAY overthinking this! Quite simply, MOA is a constant, regardless of distance, 1MOA is 1MOA. It's easier to compare accuracy between groups by stating the results in MOA than in inches because you then also have to state how far away the target was. Whereas if you say you shot a 1.5 minute group, it doesn't matter how far away the target was, it's still 1.5moa. Guys bragging about shooting a .5" group make me laugh. What was the range? I go out and shoot .25" groups all the time, at 25 yards... so that's a 1 moa group. THIS is a number we can work with, compare to other groups, etc... if I'm told I missed my target by 2 inches, well again, that doesn't tell me much. Now, if you told me I missed my target by 2 minutes, I could work with that, adjust my POA or sights with that. THIS is the point to using MOA in relation to sights/shooting.
Link Posted: 7/22/2010 11:04:05 PM EDT
Originally Posted By russellmn:
You are WAY overthinking this! Quite simply, MOA is a constant, regardless of distance, 1MOA is 1MOA. It's easier to compare accuracy between groups by stating the results in MOA than in inches because you then also have to state how far away the target was. Whereas if you say you shot a 1.5 minute group, it doesn't matter how far away the target was, it's still 1.5moa. Guys bragging about shooting a .5" group make me laugh. What was the range? I go out and shoot .25" groups all the time, at 25 yards... so that's a 1 moa group. THIS is a number we can work with, compare to other groups, etc... if I'm told I missed my target by 2 inches, well again, that doesn't tell me much. Now, if you told me I missed my target by 2 minutes, I could work with that, adjust my POA or sights with that. THIS is the point to using MOA in relation to sights/shooting.


I'm not overthinking.... I understand exactly how it all works.. what I'm just trying to show is how measuring a group in MOA isn't accurate mathematically. And ya.... the whole MOA thing has to be at a distance.. I always say my 308 is sub 0.3MOA out to 600yds if I my part(which it is) I'm just saying that if you say you have a 1MOA group at 100yds and you have a 1" group at 100yds that its two totally different things... when you measure the linear distance of a group on a target with MOA you are using a angular measurement unit to measure constant linear distances.... And this is apperently called "shooter's MOA" which is simply said that 1MOA is 1" per 100yds... which if you call it shooter's MOA that works... but say that it is "true" MOA is false.

MIke.
Link Posted: 7/22/2010 11:30:05 PM EDT
you'll never get any pussy if you try to talk about fucking with a female using your argumentative 'logic'; resolve to be lonely, with on forearm more developed than the other.
Link Posted: 7/23/2010 12:34:27 AM EDT
[Last Edit: 7/23/2010 12:35:13 AM EDT by mikeg1005]
Originally Posted By FiftyCalAl:
you'll never get any pussy if you try to talk about fucking with a female using your argumentative 'logic'; resolve to be lonely, with on forearm more developed than the other.


Definitely don't have a problem in that department, but thanks for your concern.

Mike.
Link Posted: 7/25/2010 1:41:15 AM EDT
Originally Posted By Andr0id:
Geometrically you are correct, but since you have a Isosceles triangle with two 100 yd sides and an 1 inch side, the actual difference between the length of the 1 minute of arc section and the 1 inch of the triangle are very close to zero.

To do the math, 60 x 360 x 1 inch = 21600 inches

and

100 x 36 x 2 * pi = 22618 inches

so the difference is about .05%



The difference is actually 4.7%...
Link Posted: 8/8/2010 7:50:51 PM EDT

Originally Posted By mikeg1005:

which if you call it shooter's MOA that works... but say that it is "true" MOA is false.


So basically what you're arguing is semantics? We're not using MOA in the mathematical world, we're using it in the shooter's world. So we've adapted it to what we need it to be. Maybe the people in the math world don't understand us, but they don't need to. The shooters understand us, and that's all we need. Arguing semantics, whether it be clip and magazine or "true" MOA and "shooter's" MOA is just annoying.
Link Posted: 8/16/2010 10:02:26 PM EDT
Originally Posted By RTS:
The difference is actually 4.7%...


I get 4.6 percent difference and 4.5 percent error.
Link Posted: 8/16/2010 10:51:18 PM EDT
Once someone consistantly gets to the point in their shooting skill that the .05% difference is all that is holding them back from perfection, I will be happy to give a shit.
Link Posted: 8/17/2010 12:54:43 PM EDT
[Last Edit: 8/17/2010 1:22:34 PM EDT by tt350z]
Here's how I see it.

My newest rifle happens to shoot laser beams, it is also equipped with the latest and greatest counter sniper scopes by dark ops (you know the titanium tube and Bertrillium-Zantitium multicoated optics).

The target is a real short fat bastard, I don't give a fuck about his bodies arc in MOA. The only thing I'm concerned about is how tall he is in a straight line from head to toe (secant).

He stands 51 inches tall.

I'm gonna make a head shot on a guy at 5,000 yards, but I need to dial in 1 IPHY (50 inches at 5k yards) for a perfect headshot.

If I dialed in 1 MOA instead (52.35inches at 5k yards) I miss high over his head by 1.35 inches, and 2.35 inches over my POA, DOH!

Who cares what length the arc is measured in, MOA or IPHY it's irrelevant. What's important is the secant, or better known as the straight line cutting the circle at 2 points.
Link Posted: 9/2/2010 8:42:29 PM EDT
Mike, I'm an engineer, and my wife who also shoots is an ME.
We have had this discussion as well, and came out to a similar conclusion.

We think MOA gets misused, but you have to put it in context, when it comes up at the range we just bite our tongue.


As for tt350z's diagram, I like it, secant is really what counts
However I think that at 5000 yards you'll also have the curvature of the earth to compensate for, the fat dude will be lower on the horizon making an even smaller target.
Link Posted: 9/5/2010 6:14:13 AM EDT
I'm pretty sure that with Bertrillium-Zantitium (top-secret stuff, google can only find it on counter sniper's website) multicoated optics on counter sniper scopes, it absorbs light from beyond the horizon, so fat guy is visible.

It'll also direct my rifles laser beam along the same path
Link Posted: 9/5/2010 6:20:41 PM EDT
Originally Posted By tt350z:
I'm pretty sure that with Bertrillium-Zantitium (top-secret stuff, google can only find it on counter sniper's website) multicoated optics on counter sniper scopes, it absorbs light from beyond the horizon, so fat guy is visible.

It'll also direct my rifles laser beam along the same path


I stand corrected, and since the gravity of the earth would effect both the incoming light and your out going laser identically, your shot would be spot on.



Link Posted: 9/8/2010 1:50:45 AM EDT
Since this horse is still getting beat with a clown bat, I'll chime in again...


1 moa is a cone, extending to infinity. It's not a linear measurement, if you put a target at 100 yards and a 1moa cone can cover all your shots, that's a 1 moa group. 1 moa isn't 1" at 100yds. it has a linear separation of 1.047" per 100yds. But it's still a cone that you're trying to put all your rounds inside. There is no arc for a third side, because there is no third side.
Link Posted: 9/8/2010 1:56:11 AM EDT
There is no spoon.
Link Posted: 10/17/2010 3:09:37 PM EDT
Maybe I'm under-thinking this...

I just count clicks till I hit what I'm aiming at.
Link Posted: 10/17/2010 3:35:02 PM EDT
Technically a angle subtends a specific distance.
Link Posted: 10/20/2010 1:06:17 AM EDT
I'm not sure what you're trying to argue. The arclength is very close to 1" and has a nice property of staying proportional with the distance from center of the circle (your bore) to the arc (your target.)

So to say one is within 1MOA for their groups, both the horizontal and vertical strings are within that arclength of 1.047". A minute of an arc is nothing more than the measurement of the angle and not distance. It's the arclength that is what shooters are using when they say "MOA" and it's well excepted as such.

So your statement here is off: "It is just so happens to be that at 100yds the angular measurement of 1 MOA is 1.047"... for simplicity we simply round it down to 1" as the difference is less than 5%" The "angular measurement" of 1MOA is... 1MOA. It's 1/21,600 degrees.

1/4" @ 100yds is a correct assignment as the scope is not describing the angle but the change in distance on the target itself.

You're right in saying that a MOA does not describe a distance but an angle is absolutely correct. But when we refer to "MOA" we are actually describing the arclength which is indeed a measure of distance.
Link Posted: 10/30/2010 4:33:37 PM EDT
I can get a good look at a butcher's ass by sticking my head up there, but I would rather take the bull's word for it....... Wait........ It's gotta be your bull.
Link Posted: 7/10/2011 10:52:36 PM EDT
Mike, I think you have wasted you time, not only posting this, but thinking about it........try doing a little more shooting........
Link Posted: 8/5/2011 6:39:05 PM EDT
I'd be willing to bet that the "100 yard berm" at your range isn't exactly 100 yards from..... where? the front of the bench? The back of the bench? The muzzle of your rifle? And is the bench in the shape of an arc whose center is the aforementioned target? Doubt it.
The odometer of your car probably isn't exactly right, but who cares? It's close enough.

Same with MOA=1".

Link Posted: 9/6/2011 1:10:08 PM EDT
[Last Edit: 9/6/2011 1:21:55 PM EDT by Zellers]
Originally Posted By Beavis556:
I can get a good look at a butcher's ass by sticking my head up there, but I would rather take the bull's word for it....... Wait........ It's gotta be your bull.


must important thing i pulled out of this thread..

We should just let MOA and complicated things be :P
Link Posted: 9/15/2011 7:05:01 AM EDT
Close enough.....although at longer ranges that extra .047" starts to add up. Remember it is 1.047 inches at 100 yds, 2.094 at 200,, etc....etc....

What I have found when instructing new shooters is that one of the first mistakes they make is they will use 1/4" adjustments for every distance......which is wrong,

For scopes using 1/4" @ 100 yds adjustments remember that it is different at different ranges for each click in elevation/windage on the turrets:

Example:

1/4" = 100
1/2" = 200
3/4" = 300
1" = 400

For most shooters that shoot out to about 600 yards it is close enough and practical enough to just use an inch = 1 MOA. It will put you well withing the killzone every time.
Link Posted: 9/29/2011 4:47:57 PM EDT
MOA in respect to rifle shooting isn't even a true cone. Rather it is a cone like representation of extreme spread which arcs downward and leeward at an accelerating rate. Yet, I resist going on a tangent about it. time to sin off
Link Posted: 10/4/2011 9:39:36 AM EDT
1 MOA = 1" @ 100 yards
2" @ 200 yards
3" @ 300 yards
4" @ 400 yards
5" @ 500 yards

Quit over thinking this. In reality the .047" doesn't really add up that fast, it comes out to less than 1/2" @ 1000 yards, at which point 1 MOA = 10 inches so that minute deviation is mostly irrelevant.
Link Posted: 10/4/2011 9:42:37 AM EDT
Originally Posted By MatthewCourtney:
MOA in respect to rifle shooting isn't even a true cone. Rather it is a cone like representation of extreme spread which arcs downward and leeward at an accelerating rate. Yet, I resist going on a tangent about it. time to sin off


don't post that, he might think into it more and try to take the earth's rotation into account. oops.......
Link Posted: 11/22/2011 3:35:36 PM EDT
this thread was very entertaining, thanks.
Link Posted: 12/4/2011 10:32:56 PM EDT
So I have a question.

So we have a few folks that are concerned about MOA not being exact.

What is your fix?

You have pointed out that we as shooters use MOA incorrectly.

Have you engineered the new correct targeting system?
Link Posted: 12/4/2011 10:34:15 PM EDT
So I have a question.

So we have a few folks that are concerned about MOA not being exact.

What is your fix?

You have pointed out that we as shooters use MOA incorrectly.

Have you engineered the new correct targeting system?
Link Posted: 12/4/2011 11:03:38 PM EDT
Link Posted: 12/24/2011 12:33:33 AM EDT
I am not an engineer and have only a basic understanding of MOA and still don't get it real solid yet but here ya go.

A more in-depth explanation of MOA

MOA Explained
Link Posted: 12/27/2011 8:23:53 PM EDT
This was one of the better posts I have read in a while. Drama, comedy, horror with a little documentary thrown in. A+
Link Posted: 12/27/2011 10:43:48 PM EDT
[Last Edit: 12/27/2011 10:47:19 PM EDT by FredMan]
You're beating a dead horse.

For all practical purposes, 1 MOA = ~1" @ 100 yards. The linear measurement of the arc is really 1.047", as you understand.

Unless the target was concave to the same concavity of the arc of 1/60th of 1* at 100yds.... the length would never be 1MOA.


I challenge you to find a paper target hung on any range in the country that is perfectly planar and normal to the firing line. I guarantee you that your paper target is going to have some "flex" (for lack of a better word) that will likely exceed the curvature of a sphere with a radius of 100 yards.

So, yes, you're technically correct. In the real world, however, the differences are what the physicists call negligible and are of no consequence to even the tightest-assed bullseye shooters.

ETA, that 1.047" MOA measurement is really the length of a chord intersecting your circle at the upper and lower contact points of your 1 minute arc, so it's not really along the surface of the arc. This is what happens when you try to measure a curved surface with a planar measuring device.
Link Posted: 9/22/2015 4:53:53 AM EDT
Link Posted: 3/24/2016 9:26:31 PM EDT
Originally Posted By mikeg1005:
This comes from a discussion on another gun forum.... I came to realize that we as a shooting community have adopted the phrase MOA as a term to describe accuracy/linear distance/angular distance.

I think we are doing it wrong... but simply stick with it for the sake of not getting into a semantics battle to understand eachother.

So here's my understanding.

MOA = minute of angle/minute of arc.

1 MOA is the angular measurement of 1/60th of 1 degree on a 360* circle.

It is just so happens to be that at 100yds the angular measurement of 1 MOA is 1.047"... for simplicity we simply round it down to 1" as the difference is less than 5%

So... when we look at our scope... it says on the top... 1/4" @ 100yds or 1/4MOA @ 100yds... My opinion is that the first labelling of (1/4" @ 100yds) is inaccurate and simply done not to confuse people... and here's why.

MOA is the angular distance between the infinitely long line drawn through the crosshairs of the scope and the infinintely long line drawn through the center of the barrel...

When we adjust our scopes we are changing the ANGLE of those lines... which intern would change the angular distance between them at said distance...
If you do "one click" on a 1/4MOA adjustment scope you have changed the angular distance by 1/4MOA at 100yds of the arc of the angle... this is correct.

If one says you are changing the angular distance by 1/4" at 100yds you would be wrong as you are using a linear measurment to describe a angular distance.. because linear distance doesn't change at different yardage... 1/4" at 100yds is 1/4" at 1000yds... 1MOA at 100yds doesn't have the same distance as 1MOA at 1000yds.

Same thing with targets...

One can say that their gun is a "1 MOA gun" this means that the extreme spead of the bullet impacts will be at or within a 1MOA angle at any distances... this is mathematically correct.

To say that one has a 1MOA group at 100yds which equals 1" is wrong...here is why...

You are saying that the LINEAR distance between your extreme spread of bullet holes is 1"... then you are saying that it is also 1MOA... this is wrong as you are expressing a LINEAR distance on paper using a ANGULAR measurement unit.

Here's a picture of what I mean...

http://i288.photobucket.com/albums/ll200/mikeg1005/MOA.jpg

Unless the target was concave to the same concavity of the arc of 1/60th of 1* at 100yds.... the length would never be 1MOA.

I know I am way over thinking it... but what do you guys think? I was just thinking about it and realized that we are using the mathematical terms wrong/not understanding why(I hate being in engineering)

Mike.
View Quote


Figured there was no way you weren't an engineer or math geek...




For most people 1" at 100 is one MOA. Period. End of story and who cares. Add it to the list of things made simple for the greater good.
But take comfort that a small percentage of people will understand, and care about the concavity, but without some really complicated instruments and target production the true 1 MOA will never be reached.

If it makes you feel better, I actually did start thinking about how i could create a curved target... I'm a science geek with an aversion to statistics who also is incredibly mechanically inclined...

So does this mean i have to rescind my 1 MOA shooter status and re-do it on a revamped target?? Or that myself and the other MOA's really didn't accomplish anything except making some really small groups??? sigh... [kicks dirt and shuffles back to work]
Link Posted: 12/23/2016 4:54:23 AM EDT
What a ridiculous thread.

An MOA gun can't shoot 1" groups at 100 yards and 5" groups at 500 yards. Groups don't work like that. Groups open up with more rounds OR more distance and no gun holds its angular group size from one distance to another unless you decrease round count. This is statistical fact in real world use.

I shoot mils. MOA is for Fudds.
Link Posted: 12/24/2016 11:17:13 AM EDT
I believe MILs operate just like MOAs with respect to this conversation.

(from the web, credit loose rounds)
"There are 360 degrees in a circle and each degree is divided into 60 minutes. If we round to the nearest 1/100 of an inch, at 100 yards 1 degree measures 62.83 inches. One MOA, 1/60 of that, measures 1.047"

"What is a MIL? MILS (milliradians) is another angular measurement. There are 6.2832 (p x 2) radians per circle. There are 1,000 mils per radian so, there are 6,283.2 mils in a circle. There are 21,600 MOA in a circle, so a little quick division determines there are 3.4377 MOA per mil. At 100 yards, 3.4377 MOA equals 3.599 inches (3.4377 x 1.047). Rounded up, one mil equals 3.6 inches at 100 yards."

(back to my feeble brain)
At the end of the day you're dealing with the same types of measurements. Range, angular divergence and a secant at a known range.

So as to your comment MOA's are for fudds… No they aren't. They're for people who shoot known ranges, like to move things more precisely (.1 mil at 100 yards=.36" while .25 MOA is REALLY close to 1/4" at 100, there are also 1/8" click target scopes) MIL's are the easy button for many as long as you have a MIL reticle AND MIL turrets but they less precise. So are you a target shooter or do you shoot in varying conditions at varying ranges and like using ballistic computers?

To your final comment about groups always opening up from 100 to infinity. The physical size of the group will absolutely get larger. The MOA may vary at ranges.
(from people way smarter than me, credit american rifleman online….)

"Dave Emary is one of the top ballisticians in the firearm industry. Officially he is Hornady Ammunition’s Chief Ballistic Scientist. He is a contributor to the world standard of guns and ballistics, SAAMI (Sporting Arms and Manufacturers Institute). This organization is comprised of mathematical and technical geniuses and they don’t spout B.S.

Emary said, “It’s not very common, but yes it is possible. It is primarily with very heavy for caliber and long for caliber bullets or bullets that are grossly over-stabilized. In both these cases it can take the bullet a long time to “go to sleep” or to damp out all the “wobble” from the muzzle. This would cause the bullet to shoot better at longer ranges than at short ranges. Several cartridges that exhibit this behavior are the .338 Lapua and the 50 BMG.”

I agree with one of the earlier post. This is a pretty good read. Has comedy, drama, some good facts and the stick art is amazing!

Merry Christmas
Link Posted: 3/22/2017 4:14:50 PM EDT
[Last Edit: 3/22/2017 4:16:33 PM EDT by axarob44]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By DevL:
What a ridiculous thread.

An MOA gun can't shoot 1" groups at 100 yards and 5" groups at 500 yards. Groups don't work like that. Groups open up with more rounds OR more distance and no gun holds its angular group size from one distance to another unless you decrease round count. This is statistical fact in real world use.

I shoot mils. MOA is for Fudds
.
View Quote
Link Posted: 3/22/2017 5:13:32 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By tt350z:
Here's how I see it.

My newest rifle happens to shoot laser beams, it is also equipped with the latest and greatest counter sniper scopes by dark ops (you know the titanium tube and Bertrillium-Zantitium multicoated optics).

The target is a real short fat bastard, I don't give a fuck about his bodies arc in MOA. The only thing I'm concerned about is how tall he is in a straight line from head to toe (secant).

He stands 51 inches tall.

I'm gonna make a head shot on a guy at 5,000 yards, but I need to dial in 1 IPHY (50 inches at 5k yards) for a perfect headshot.

If I dialed in 1 MOA instead (52.35inches at 5k yards) I miss high over his head by 1.35 inches, and 2.35 inches over my POA, DOH!

Who cares what length the arc is measured in, MOA or IPHY it's irrelevant. What's important is the secant, or better known as the straight line cutting the circle at 2 points.
http://i778.photobucket.com/albums/yy62/tt350z/moa5.jpg
View Quote
MS Paint of the month right there
Link Posted: 3/22/2017 5:22:30 PM EDT
what the fuck?
Top Top