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-   -   MOA is not a Canadian cow! (http://www.firearmstalk.com/forums/f18/moa-not-canadian-cow-47969/)

canebrake 09-08-2011 04:19 PM

MOA is not a Canadian cow!
 
If you have any corrections/additions please PM me. - cane

Using and Understanding Minute of Angle (MOA)

You should understand that an English inch and a Minute of Angle (MOA) is not the same thing. They are units of measurement that happen to be extremely close in value. However, they are close enough together that for the rest of this explanation please simply round down to an inch.

Exact Minute of Angle (MOA):
1 MOA = 1.0471996 inches @ 100 yards.
1 MOA = 5.24 inches @ 500 yards.
1 MOA = 10.47 inches @ 1000 yards.
Rounding MOA:
1 MOA @ 100 yards = 1 inch
1 MOA @ 200 Yards = 2 inch
1 MOA @ 300 yards = 3 inch
1 MOA @ 400 Yards = 4 inch
1 MOA @ 500 yards = 5 inch
1 MOA @ 600 Yards = 6 inch
1 MOA @ 700 yards = 7 inch
1 MOA @ 800 Yards = 8 inch
1 MOA @ 900 Yards = 9 inch
1 MOA @ 1000 Yards = 10 inch
Minute of Angle as it applies to group size and drop:

MOA is used to measure group sizes.
A 1 inch group @ 100 yards is referred to as a 1 MOA group.
A 2 inch group @ 100 yards is a 2 MOA group.
At 100 yards it seems simple enough to understand. However, it can get confusing if you’re not used to the terminology when you move beyond 100 yards.

For example:
A 3 inch group shot at 300 yards is also a 1 MOA group.
A 6 inch group shot at 300 yards is a 2 MOA group.
A 1 inch group shot at 300 yards is a .5 MOA group.
Another way to look at it is like this:
MOA @ 700 yards is 3.5 inches
1 MOA @ 700 yards is 7 inches
2 MOA @ 700 yards is 14 inches
3 MOA @ 700 yards is 21 inches
or
3.5 inches @ 700 yards is MOA
7 inches @ 700 yards is 1 MOA
14 inches @ 700 yards is 2 MOA
21 inches @ 700 yards is 3 MOA
Calculations:

How many inches equal 4 MOA at 700 yards?
* (MOA x yards) / 100 = inches
(4 MOA x 700 yards) / 100 = 28 in
*You can drop the last step and make the calculations easier by moving the decimal on the yards two places to the left.
How many inches equal 4 MOA at 700 yards?
(4 MOA x 7.00 yards) = 28 in

How many MOA equal 21 inches at 700 yards?
* (inches / yards)100 = MOA
(21 inches / 700 yards) 100 = 3 MOA
*You can drop the last step and make the calculations easier by moving the decimal on the yards two places to the left.
How many MOA equal 21 inches at 700 yards?
(21 inches / 7.00 yards) = 3 MOA

5 inches = 1 MOA how many yards away is the target?
(Inches x MOA)100 = Yards
(5 inches x 1 MOA) 100 = 500 yards


Minutes of Angle and Rifle Scopes:

Most hunting and target scopes adjust in Minutes of Angle (MOA). The most common adjustment is or .25 MOA per click. Although not as common, there are scopes that adjust in 1/8, 1/6/, 1/5, 1/3, , and 1 MOA.

MOA at 100 yards literally means that each time the scope turret is clicked the bullet impact will move or .25 inches.

To move the bullet impact 1 inch you would need 4 clicks (.25 x 4 = 1)

Example:

When sighting in a rifle the bullet needs to move up 5 inches to hit the center of target. 5 in / .25 in = 20 clicks or you could think of it like this: need to move 5 inches, 4 clicks per inch, 5in x 4 clicks per in = 20 clicks.

Another application for understanding MOA and scope or sight adjustment is when shooting longer distances. Rifle is sighted in at 100 yards. Your ballistic program tells you that you need to come up 20 MOA to shoot at 600 yards. 20 MOA / .25 = 80 clicks Or 20 MOA x 4 clicks per MOA = 80 Clicks


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