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Thread: MOA

  1. #1


    OK on the British Army thread there was talk of MOA (Minute of Angle, I think).
    In laymans, or a Wildfowlers term what is an MOA?

    Is it the ability of a given rifle to put say 5 shot's into a 1" circle at 100yds and therefore a 4MOA 5 shots in a 4" circle at a 100yds?

    Nuffink teknikal to confuse my brain please


  2. #2

  3. #3
    Yes, it's 1 minute of angle. Like there are 360 degrees in a circle there are 60 minutes in a degree.

    If you were to fire a laser beam out of your barrel onto the target 100 yds away, then move the angle of the barrel up by one minute of angle the dot would move up approximately one inch.

    If you remember your trigonometry , tan(angle)=Opposite/Adjacent

    Where angle = 1 minute = 1/60 degrees
    Adjacent = 100 yards = 3600 inches

    Opposite = how much the dot moves

    which = 3600 * tan(1/60) = 1.05"

  4. #4

  5. #5

    move up one minute

    I am so glad I am really normal ,Tone,

  6. #6
    Yep I like laser beams to Alex being a bit of a trekkie

  7. #7

  8. #8
    I'd sooner get in close with my light sabre! 8)

  9. #9
    But is it Minute of Angle or Minute of Arc?

    Firearms, astronomy or mathematics.

    What's the correct terminology - not just the one that's in common use throughout the firearms industry - discuss!

  10. #10
    Just to confuse even more, you could talk about milliradians

    2 pi radians are equivalent to 360 degrees, which is rather handy because 2 * pi * radius gives you the circumference of a circle, then if you want arc length, you do angle in radians * radius....

    Still with me? For small angles, the arc length is very close to sine or tangent of the angle * length, so instead of having to resort to trigonometry, you just go for angle * distance...

    With the 'milli' prefix, you have 1000 milliradians in a radian, so what you end up with is: milliradians / 1000 * distance = size

    In metric terms, 100m = 10000cm, so 1 milliradian is 10 cm at 100m

    In yards, 100 yards = 3600 inches so 1 milliradian is 3.6 inches at 100 yards


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