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Shooting Tips

Meaning of MOA?

by Scott E. Mayer   |  May 24th, 2011 6

Q: I’m new to the shooting sports. I often hear gun accuracy expressed in terms of “MOA,” but with no explanation of what a MOA is. What is a MOA? — Charles B.

A: MOA stands for “Minute Of Angle,” which is a unit of angular measurement. When the accuracy of a gun is given in minutes of angle, it is possible for a person to know approximately what size groups the gun shoots within its effective range.

There are 360 degrees in a circle, and 60 minutes of arc in each degree, totaling 21,600 minutes of angle in a complete circle. Imagine the shooter is at the center of a circle, and that the target is on the edge of that circle. The distance, or range, from the shooter to the target is also the radius [R] of the circle.  For any given range or radius [R], one minute is equal to 2πR÷21,600.

If the range is 100 yards, that distance is equal to 3,600 inches. When we plug 3,600 in for R in our formula, the result is (2)(3.1416)(3,600)÷21,600 = 1.0472 inches. Therefore, at 100 yards, one MOA is equal to 1.0472 inches. The formula works for any range. If the range is 500 yards, one MOA equals 5.2360 inches.

Many shooters equate one MOA to one inch at 100 yards, 2 inches at 200 yards, and so on. Often, they will call a gun that shoots one-inch groups at 100 yards a “one-MOA gun.” Since targets are usually on an inch grid, and sight adjustments in fractions of an inch, the difference between “true” minutes of angle and “shooters’” minutes of angle is academic at close range.–sem

  • Bob D.

    What a rip off. You finally find a place where the definition of a MOA is listed, and when you try to print this write up, it prints 8 pages of junk, and never prints the listed definition of a MOA. If a person prints this, will it be compromising Petersen's trademarks or jeopardizing their trade secrets? It is nice to see where this definition is listed, but I do not have access to a computer every time I need to reference the definition. Come on, get real.

    • lionzine

      Wow, Bob… you'd think Rifle Magazine owes you something.

  • Peter Grens

    Bob
    I don't think you know how to print off internet material.
    You should get real
    Paul

  • J.J.

    I'm not savy on a computer, but all I did was highlight the area or data that I needed, went to "file", clicked on "print", then the printer window popped up and I clicked on the "selected" button and Bingo… One minute from start to finish and that's with a slow printer….

  • chinaMike

    Thanks for the full explanation. Am new to sporting rifles and love your publication. Great resource.

  • Mr.America

    Nicely written I refer people to read this cause I get tierd of fighting with them about MOA till I'm blue in the face

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