Moa

Discussion in 'Optics & Mounts' started by mbpike, Jul 29, 2009.

  1. mbpike

    mbpike New Member

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    So I feel like a dummy here but I have to ask. I recieved a BSA holosight yesterday ( I could not turn down free) and it has 4 reticle settings. It has 3 M.O.A, crosshairs, 10 M.O.A crosshairs and a 65 M.O.A with 3 M.O.A dot. Now it seems to be a decent sight and yes I know it was cheap but my question is what does the MOA settings mean. Can someone stear me in the right dirrection so I'm not so lost anymore. Thanks for all the help.

    Matt
     
  2. orangello

    orangello New Member

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    Minute of arc - Wikipedia, the free encyclopedia "It is popular because 1 MOA subtends approximately one inch at 100 yards, a traditional distance on target ranges. A shooter can easily readjust his rifle scope by measuring the distance in inches the bullet hole is from the desired impact point, and adjusting the scope that many MOA in the same direction. Most target scopes designed for long distances are adjustable in quarter (¼) or eighth (⅛) MOA "clicks". One eighth MOA is equal to approximately an eighth of an inch at 100 yards or one inch at 800 yards."

    I had heard the term before, but had to look for a way to define it. All i ever remember is 1" at 100 yards, and i never get to shoot that far here (too many pine trees).
     

  3. mbpike

    mbpike New Member

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    ok so I have a grasp on the idea of MOA but why would they make different reticles on optics with different MOA I guess I'm still pretty darn lost
     
  4. Dillinger

    Dillinger New Member

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    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.
     
    Last edited: Jul 29, 2009
  5. orangello

    orangello New Member

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    So, is the 10MOA a bigger and easier to line up quickly than the 3MOA version? I would think that bigger dot or cross would be easier to see & line up on target quickly but not quite so accurately because the bigger dot or cross covers more of the target.

    Maybe someone with a similar setup will have a better answer. edit* And there he is. :)

    (the MOarc article had a section on MOAngle, Wiki must not like MOAngle as much. We are always hearing about Joan of Arc, but never about Joan of Angle.)
     
    Last edited: Jul 29, 2009
  6. Dillinger

    Dillinger New Member

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    Orange - In a word, yes, basically.

    Here's the rub though. A 10 MOA "dot" would essentially cover a 10" pie plate at 100 yards. So, looking through the scope, at the reticle, you would not be able to see the pie plate when you were right on target.

    Now, up close, this would be about the size of one of those orange/red dabbers that the Bingo people use to cover up their numbers, it would be the size of a quarter or so. Lining that up on a man's chest would also be quite easy, but it would cover a surface area that might not allow you to see all of your target, thus shooting someone in the head would be difficult.

    Personally I would never use a 10 MOA reticle, even in a CQB gun, but that is just me. *shrug*

    JD
     
  7. orangello

    orangello New Member

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    What would be cool (in my opinion) is a similar device that flashed the 1MOA, then the 3MOA, then the 10MOA, in contrasting colors and sequentially. You could aquire the target then tighten up if needed.

    . . +

    Of course, who would want a purple crosshair?
     
  8. mbpike

    mbpike New Member

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    Ok I get it now, Thank all of all so much. At first I was not sure why the sight would offer 4 different choices to choose from but now I get it. I'm a big fan of the 65 MOA with the 3MOA dot
     
  9. orangello

    orangello New Member

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    Roseanne standing behind Kate Moss. :D
     
  10. Dillinger

    Dillinger New Member

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    The other way around, but I like your analogy... LOL

    JD
     
  11. matt g

    matt g New Member Supporter

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    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.
     
  12. Dillinger

    Dillinger New Member

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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
     
  13. orangello

    orangello New Member

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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.
     
  14. matt g

    matt g New Member Supporter

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    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.