

07292009, 09:15 PM

#11

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Quote:
Originally Posted by Dillinger
I am afraid I don't understand the question.
A 3 MOA reticle covers 3 inches of the target at 100 yards, that sounds like an ideal close quarters scope, but for distance shooting, not to much.
A Fine Duplex reticle would have very thin lines, a very thin dot at the center ( on some ) and would be pretty bad for up close shooting. However, at a distance, the reticle won't cover your target, so you can do fine, print style shooting.
In a close quarters scope, you want a good sized reticle that you can cover a man's chest with, in a hurry, and pull the trigger. If you have a tiny, thin, wire reticle, you can't do that real quick and with both eyes open....
Does that help??
JD
PS  It's Minute of ANGLE, not Minute of Arc. The term translates to roughly 0.47" at 1,000 yards.

Actually it is minute of arc, but minute of angle is the more commonly used term. Being that an arc is an angle they mean the same thing.



07292009, 10:44 PM

#12

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No, it isn't Minute of Arc. Wikipedia is wrong.
The Minute of Angle corrolates directly to the number of degrees in a circle, 360 degrees. Each of the 360 degrees is then divided into 60 MINUTES.
Thus, a 100 yard radius CIRCLE is 628.32 yards or 22,619 inches. A little dividing for math and you come up with, exactly, 1.047 inches per minute.
So, you change your scope by 1 MOA and you get a change of 1.047 inches at 100 yards.
Now, if you can get Art Pesja to admit that it's Minute of Arc, I might consider looking at the statement. But, when the Godfather of Ballistics says that it's Minute of Angle, I am going with him and not anyone else on the Interwebz.
Especially Wikipedia....
JD



07292009, 10:50 PM

#13

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I posted from Wiki because it's quick & usually easy to understand.
"Calculating the physical equivalent group size equal to one minute of arc can be done using the equation: equivalent group size = tan(MOA/60) × distance. In the example previously given and substituting 3600 inches for 100 yards, tan(1 MOA/60) ∙ 3600 inches = 1.0471975511966 inches." from teh Wiki
They get the same answer.



07302009, 10:33 PM

#14

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Quote:
Originally Posted by Dillinger
No, it isn't Minute of Arc. Wikipedia is wrong.
The Minute of Angle corrolates directly to the number of degrees in a circle, 360 degrees. Each of the 360 degrees is then divided into 60 MINUTES.
Thus, a 100 yard radius CIRCLE is 628.32 yards or 22,619 inches. A little dividing for math and you come up with, exactly, 1.047 inches per minute.
So, you change your scope by 1 MOA and you get a change of 1.047 inches at 100 yards.
Now, if you can get Art Pesja to admit that it's Minute of Arc, I might consider looking at the statement. But, when the Godfather of Ballistics says that it's Minute of Angle, I am going with him and not anyone else on the Interwebz.
Especially Wikipedia....
JD

Any portion of a circle is a parabola, which is also an arc. Any arc is also a denotation of an angle, which is why either is correct.
Surveyors and engineers refer to it as minute of arc, gun folks refer to it as minute of angle.



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