MOA Explained

Discussion in 'Beginner Articles' started by Texas1911, May 20, 2010.

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  1. Texas1911

    Texas1911 TGT Addict

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    MOA Basics

    One confusing aspect of using a scope is the concept of MOA. The term MOA is derived from a geometric measurement, it describes 1 minute within 1 degree. Since there are 60 minutes in a single degree, it's a relatively small adjustment, but when you factor in the shot distance it becomes a very big part of the shooting solution.

    When you are sighting in a hunting rifle you often are going to be shooting within 100 yards of your target, and because of this is why people will often express 1 MOA as 1" at 100 Yards. However, if you are shooting at 50 yards, or even 200 yards, the value of 1 MOA changes. This occurs because MOA is a measure of angle, not distance.

    [​IMG]

    The above picture should explain the concept better. Notice the difference in how much the scope moves relative to distance.

    Identifying the MOA Adjustment on a Scope

    [​IMG]

    When you remove the turret covers on your scope you should see something written on the top of the turret. Some common examples are as follows:

    Click Adjust Scopes
    1/2 MOA
    1/4 MOA
    1/8 MOA

    Friction Adjust Scopes
    1/4 MOA
    1 MOA
    2 MOA

    This is based off of my experience with a wide range of scopes. The vast majority of scopes on the market today are 1/4 MOA, with the 1/8 and 1/2 MOA scopes fulfilling more of a specialized role like benchrest shooting (1/8 MOA) or tactical or short range applications (1/2 MOA). There are a number of older Leupold and Redfield scopes that are in 1 and 2 MOA. These almost exclusively are friction type adjustments and can really get people frustrated on the firing line if they don't understand the adjustment.

    If nothing is written on the scope, run the target out to 50 yards and look through the scope with the rifle firmly set in a benchrest or bag setup, don't put any pressure on the rifle with your body while you are doing this. With the reticle aimed at a fixed point, turn the elevation turret 8 clicks, or one large tick mark on the friction type scopes. Note how much the reticle moved. If it moved 2" then you have a 1/2 MOA scope, conversely if it moved 1" then you have a 1/4 MOA scope, and if it moved 4" or more then you have a scope equal to or above 1 MOA.

    Lastly if you don't know the adjustment, it should be found in the manual for the optic, or at worst case you can call the manufacturer.

    Applying MOA to Sighting in the Gun

    When you start out with a fresh scope:gun combo you are going to want to start at a close known distance, for the sake of this article that will be 25 yards and we will be using a 1/4 MOA scope. Let's say the first shot is 3" to the right of the bullseye, how do I know how many clicks I should move?

    1 Click = 1/16" at 25 Yards

    3" of Movement = 16 x 3 = 48 Clicks Left

    What if it is 8" high and 2" left at 100 Yards?


    1 Click = 1/4" at 100 Yards

    8" of Elevation = 4 x 8 = 32 Clicks Down
    2" of Windage = 4 x 2 = 8 Clicks Right

    What if my last shot is 4" high and 2" right at 400 Yards?

    1 Click = 1" at 400 Yards

    4" of Elevation = 4 / 1 = 4 Clicks Down
    2" of Windage = 2 / 1 = 2 Clicks Left

    Notice the difference when you've exceeded 400 yards. You start dividing to find the number of clicks since a single click is a value over one (not a fraction). This can get confusing when you are using odd-ball ranges like 700 yards with a 3/4 MOA iron sight. That's where pen and paper along with a calculator come in handy, and/or using a chart similar to the one below.

    Here's a quick chart for you to use in the field. Once you do it a few times you'll remember it by memory.

    [​IMG]

    Distance in yards on the left, and the values in the chart are the amount of movement per click of adjustment.

    Questions or Something Missing? -
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