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#### pittbug

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I'm trying to understand calculating MOA, please doublecheck my math and logic.

I understand that calculating 1MOA at 100 yards is as follows:

(assuming pi = 3.1416)

Circumference in inches:
100 x 2 x pi x 12 x 3 = 22619.52

There are 360 x 60 = 21600 minutes in 1 full circle

So 1 MOA at 100 yards = circumference / 21600 = 1.0472 inches

The first time I took my father-in-law's 308 out to the range, my best group was about 1.5inches at 200 yards, so..

200 x 2 x pi x 12 x 3 = 45239.04 inches

1 MOA at 200 yards = 2.094 inches.

Now calculating MOA from my group size:
1.5 - 0.308 = 1.192

1.192 / 2.094 = 0.57MOA at 200 yards?

Is this correct?

Thanks

#### muzzleblast

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I guess so :lol:

I like the simple version. MOA is 1 inch at 100, 2 inches at 200, etc.

Your group was .75 the way I keep it simple.

#### pittbug

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Muzzleblast said:
I guess so :lol:

I like the simple version. MOA is 1 inch at 100, 2 inches at 200, etc.

Your group was .75 the way I keep it simple.
So you don't subtract the diameter of the bullet?

#### ekaphoto

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pittbug said:
Muzzleblast said:
I guess so :lol:

I like the simple version. MOA is 1 inch at 100, 2 inches at 200, etc.

Your group was .75 the way I keep it simple.
So you don't subtract the diameter of the bullet?
Depends on how you measure the group. Lets say you are using a .308 diameter bullet. At 100 yards you shoot a group. If you measure outside edge to outside edge at the widest point, lets say it is 1.308 in, than you subtract the diameter of the bullet and get 1 in.

Lets say the two farthest bulletts were straight above each other. Measure from the top of the top bullet to the top of the bottom bullet hole, you will get 1 in. This only works if the bullett holes are NOT touching. That is the same as measuring center to center.

Like muzz said keep it simple, 1
in at 100, 2in at 200 etc. It is simple and easier, also has NOTHING to do on how you measure you bullet holes.

Confused now? I am lol

#### muzzleblast

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lol I am too. You did a really good job of explaining it Eka, I should have done better. Thanks for straightening me out.

Yup, with a 1.5 MOA group and a .308, holes wouldn't be touching, so I wouldn't subtract caliber the way I measure.

#### pittbug

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eka: ok... thanks for the explanation.

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