MOA?

[Colorado Ntv]

Could someone give me an educated explanation as to what this means? MOA and sub MOA.

 

[RayDog]

1 MOA is about 1" at 100 yards(atually 1.047 I think). Or I should say 1" per 100 yards.
1 MOA at 100 is 1"
1 MOA at 200 is 2"
1 MOA at 300 is 3"
1 MOA at 1,000 is 10"

So when you talk in MOA the size depands on the range. A .5 MOA group at 100 yards is 1/2"

A .5 MOA group at 600 yards is 3"

When you turn your knobs on your scope to adjust MOA at 100 yards 1 MOA dialed into your scope will move impact 1". But at 700 yars that same 1 MOA would move impact 7"

Hope that helps

 

[Colorado Ntv]

Thank you! So if a particular rifle company says I should expect about 1/2"moa at 100 yds, they are suggesting a 1/2" group@100, 1" @200 and so on?

 

[Mal H]

MOA = Minute Of Angle

RayDog explained it well, but I would change his statements where he uses the term "impact" to "point of aim". The point of impact of a bullet is governed by gravity as well the settings on the scope.

 

[pcf]

An angles arc is measured in degrees, degrees can be broken down into minutes.

360 degrees in a circle.
60 minutes of angle in a degree.
Radius of a circle is 2(radius)(pi)

if your shooting at 100 yards you're 3600 inches from the target.

The circumference of the a circle with a radius of 100 yards is (3600 inches * 2 * 3.14159) = 22691.448 inches

An arc of degree would be Radius/360 which is (22691.448/360) = 62.8138 inches.

An arc of the minute of angle would be one arc of degree/60 which is (62.8138/60) = 1.0472 inches at 100 yards

In case you ever wonder where the number comes from.

Edited: the math is right the terminology isn't..........

 

[Colorado Ntv]

That was exactly what I was looking for, thank you very much!

 

[RayDog]

Looks like your in NO CO also. You can drive up and check it for for yourself if you want. Zak and I spend a good amount of time shooting at things far away. Drop me an email or PM

 

[ArmedBear]

Hey, what happened to Quotes?

WRT the 1/2" at 100, 1" at 200, etc...

If a rifle company promises 1/2" at 100 yards, that is a very good rifle, so you might expect 1" at 200 yards in that case.

However, it's not always that simple. Sometimes, groups are 1.5 MOA at 100 yards but 1 MOA at 200, or the other way around.

Air turbulence of a given round, rifling, and other factors, none of which I fully understand, affect accuracy at given distances. Wind does, too, of course, in real-world hunting situations or windy target ranges, but I'm just talking about intrinsic accuracy.

Others know more about this than I do. A lot more. I like shooting little disc-shaped things flying around, with a shotgun.

 

[Colorado Ntv]

Yeah, Im somewhat of a skeet guy myself, hence the newbie question Thanks to everyone for helping me out, I think I like it here

 

[Merkin.Muffley]

I've got a question about this as it relates to dot scopes. A scope I've been looking (Aimpoint Comp ML3) has both 2MOA and 4MOA dots. What does this mean when I look thru the scope?

 

[KIDGLOCK]

It means that the DOT covers 2MOA at 100 yards. Thus 2inches coverd at 100.
4 MOA = 4inches @ 100.

 

[GoRon]

Copied this from a thread a while ago. I wish I would have saved the authors name also, he deserves credit.

A circle is divided into 360 degrees.

Each degree is divided into 60 minutes.

If you pretend you are at the centerpoint of a circle and the target is on the circumference of the same circle then you can measure your accuracy in minutes of angle.

So, let's say you are 100 yards away from your target.

That makes the radius of the imaginary circle 100 yards. We can calculate the total circumference of the circle using 2 x pi x radius.

The total circumference of the circle is then 628.32 yards. Divide the circumference by 360 to get the distance on the circle defined by a single degree.

One degree of angle on a 100 yard radius circle is therefore 1.745 yards.

Now, divide that by 60 to get the distance on the circle defined by a single minute.

When we do that we find that one minute of angle on a 100 yard radius circle is 0.029 yards or 0.087 feet or 1.047 inches. That's pretty close to one inch and most folks just call 1 MOA and 1 inch the same thing at 100 yards.

You can calculate what 1MOA is at any distance using the following formula.

1MOA (inches) = distance (yards) / 95.49

At 50 yards, 1 MOA is 0.52 inches
At 75 yards, 1 MOA is 0.79 inches
At 150 yards, 1 MOA is 1.57 inches
At 250 yards, 1 MOA is 2.62 inches

Note that most people approximate these numbers by rounding them DOWN to the nearest quarter inch in practice. That makes it easy to calculate--simply divide the yardage number by 100 to get the APPROXIMATE value of 1 MOA in inches.
__________________

 

[JohnKSa]

Note that most people approximate these numbers by rounding them DOWN to the nearest quarter inch in practice. That makes it easy to calculate--simply divide the yardage number by 100 to get the APPROXIMATE value of 1 MOA in inches.

This should really be reduced to:

"Note that most people approximate these numbers by simply dividing the yardage number by 100 to get the APPROXIMATE value of MOA in inches."

The part about "rounding down to the nearest quarter inch" and the part about "1 MOA" wasn't very well thought out.

 

[30Cal]

If you are holding a firearm, then 1MoA is one inch. I've never seen or heard of anyone performing trigonometric calculations on the range. I also very much doubt that there are many shooting ranges that have been regulated to two decimal places (ie 100yds vs 100.00yds).

Ty

 

[JohnKSa]

Yes--and if you're holding a firearm, then 450240=450436. (Someone will figure that out pretty soon--and no, it's NOT sarcasm.)

From a practical standpoint, you're right and sometimes that's all people want to know. But it's interesting to some folks to know the origins of terms and the exact values instead of the practical approximations.

 

[trbon8r]

MOA is the size of the 5 round groups that gun writers shoot with iron sighted rifles on a regular basis. Of course they usually neglect to tell you about the vise grip thingamajig they had the rifle bolted to while testing.

 

[Mal H]

Yes--and if you're holding a firearm, then 450240=450436.

Does the gravitational constant enter into that by any chance? If so, the equality statement should be changed to "450240 becomes 450436". (I won't vouch for the exactness of the statement; I'll take your word for it. )

 

[Infidel]

Yes--and if you're holding a firearm, then 450240=450436.

I thought it was 450437. No wonder my power factors were off.

But it's interesting to some folks to know the origins of terms and the exact values instead of the practical approximations.

That's me, to a 'T'. Arcane factoids are such fun!

Which brings up ... Dividing the circumference of a circle into 3600 parts and so on does not result in the correct number for a minute of angle at 100 yards. It does result in the distance a minute subtends measured along the circumference. For target purposes, the minute is measured perpendicular to a radius, and is given by the tangent of the angle (1 minute) times the radius of the circle. The two numbers at 100 yards are 1.047197551 and 1.047197581, a significant difference of 0.000000030 inches (at 100 yards). The two numbers are so close only because the tangent approaches the angle as they both approach zero.

 

[Bwana John]

Arcane factoids are such fun!

I would think that to use a tangent relationship, the middle of the group should be used, not one edge or the other. So it would be- 2 times the arctan of one half the groupsize over the distance to target.

I've never seen or heard of anyone performing trigonometric calculations on the range.

Windage and elevation are solved using trigometric functions all the time in precision long range shooting.
But we might just be nerds, calc even comes up at the range, never mind trig!

 

[JohnKSa]

Does the gravitational constant enter into that by any chance? If so, the equality statement should be changed to "450240 becomes 450436".

My understanding is that the 450240 was a typo that "became fact" before anyone figured it out.

Since the gravitational constant varies based on your location, it's hard to get too worked up about it--especially since any number that looks like 450xxx will give you an answer that is correct to within 3%.

Someone oughtta start a thread called "math vs the gun world" or something like that.

The two numbers at 100 yards are 1.047197551 and 1.047197581, a significant difference of 0.000000030 inches (at 100 yards).

Infidel,

I always put a slight curve in my target paper to account for that.

 

[Infidel]

I would think that to use a tangent relationship, the middle of the group should be used, not one edge or the other. So it would be- 2 times the arctan of one half the groupsize over the distance to target.

Yes! I have tried explaining the idea of twice the tan of half the angle, and I usually get blank stares and get sent to fetch the next round. Thank you. Then there's using the sin, measuring to the head instead of to the feet, or measuring to the belt buckle and using twice the sin of half the angle. Or, maybe average all of the above? (Uhhhh ... arctan is an angle. That is, arctan 1.04719/3600 = 1/60 degree (= 1 minute) (more or less)).

Where are the paper napkins when we need them?

I always put a slight curve in my target paper to account for that.

Wow. I never thought of that. I so like learning things. Thank you. Now, I gotta make a curved template for my targets....

 

[Bwana John]

arctan 1.04719/3600 = 1/60 degree (= 1 minute) (more or less)).

Real men use radians!