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Discussion Starter · #1 ·
I am new to "precision" shooting. I have always zeroed a rifle and went hunting. What is the formula or how do you measure your grouping to get your group size in referenc to MOA. Any good reading material on exactly what Minute Of Angle means and how to understand and use that reference. Thanks
 

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Here's a pretty good website that I've read through a couple of times about Mil dots and MOA.

http://www.mil-dot.com/Mil_Dot_Information.htm

For practical purposes 1 MOA at 100 yards is the same as 1" at 100 yards.

But 1 MOA at 200 yards would be about a 2" group at 200 yards. You can see that MOA is more of an "angular" measurement.

For example, someone may say, "my gun shoots 1 MOA at 1,000 yards/meters". Well, that's a 10" group at that range but it's still 1 MOA because 1 "minute of angle" would cover about 10" inches at that range.

I measure my groups from outside to outside, and then subtract the caliber of the gun I'm shooting.

For example, I just shot a 3 shot group a couple of weeks ago that measured... .707" Subtracting .308 from that measurement gives me the "actual group size" at .399"
 

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I agree with everything except subtracting the bullet diameter. If you measure a .30 cal hole in a target it won't be .308. Usually it will be a few thousands smaller depending on the target paper. That will only marginally affect group size but if you're shooting in a match it will be the difference between first and last place.
 

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Interesting point. Do they score matches like that?

I've always heard to subtract the caliber of the bullet you are shooting. I wonder if the paper could "contract" just a bit as the bullet goes through the paper.
 

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SemperFi said:
Interesting point. Do they score matches like that?

I've always heard to subtract the caliber of the bullet you are shooting. I wonder if the paper could "contract" just a bit as the bullet goes through the paper.

My .223 rounds which actuall measure .224 leave a .219-.221 hole depending on which targets I'm using.
 

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Discussion Starter · #6 ·
Thanks that helps a lot. Next time I am at the range( I have a 100 yard range in my back yard, but ranch life keeps me so busy I don't use it as much as I would like. Plus it has been 100+ degrees everyday.) I will put this to use and post a picture with range report. Can someone talk me through posting images. I have been unsuccessful at this point.
 

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For posting pics... some use Photo Bucket. http://www.photobucket.com/

You have to sign up for an account and what not.

I just use my own server and go the more "manual" approach.

If you have more questions about it, just post back and someone will be able to help you out.

Does anybody know of any better alternatives to Photo Bucket?
 

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I use the quick and easy method.

Measure the group size edge to edge (the black rings, also called lead rings) and then subtract the bullet diameter.

This isn't the way BR shooters do it but it is quick and nasty.

There is a free program that will do this for you, but you do need a scanner, called On Target Precision Calculator.

http://www.ontargetshooting.com/
 

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Now that sure beats looking through a magnifying glass at a caliper. I did a few of my old targets and it measured smaller than what I had called them. I really like that.
 

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you can even do a quick center to center of the two farthest holes of the group.........
 
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