Measuring MOA for groups?

H

hawk-i

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Just want to make sure I'm doing this properly.

If my 100yard group measures outside to outside 1.237 inches with .308 bullets the center to center spread is .929 x .9549 = .887 MOA at 100 yards....but at 100 meters ='s .887MOA x .9174 = same group at 100 meter is .814 MOA. Is this correct?

Thanks
 
That is correct. divide the group size in inches by 1.047 at 100 yards to get MOA, divide group size by 1.141 at 100m to get MOA.

100 meters is just under 10% further than 100 yards, so the MOA for same size group at 100 m would be just under 10% less.

Dan
 
A flaw in the system is that you need to subtract the diameter of the bullet hole in the target, not the diameter of
the bullet. The difference is enough to depress people who measure groups with a caliper.
 
That's why I've been using the On Target calculator. All you need is a photo of your group and a reference length, usually the diameter of the target or size of the paper it's on. Fairly accurate as long as you take your picture at a right angle.
 
To convert yards to MOA
100 yds = 1. 200 yds = 2. 300 yds = 3. .... and so on
Group size = "X" inches
Divide .... X by 1 by 1.047 = MOA at 100 yds
Divide .... X by 2 by 1.047 = MOA at 200 yds
Divide .... X by 3 by 1.047 = MOA at 300 yds

To convert meters to MOA
100 m = 109.4 yds
Group size = "X"
Divide..... X by 1.094 by 1.047 = MOA at 100 M
Divide..... X by 2.19 by 1.047 = MOA at 200 M
Divide.... X by 3.28 by 1.047 = MOA at 300 M
 
Last edited:
Dogleg said:
A flaw in the system is that you need to subtract the diameter of the bullet hole in the target, not the diameter of
the bullet. The difference is enough to depress people who measure groups with a caliper.
Click to expand...

Yes! Measure what a single bullet hole cuts in that target. Different targets can make different size holes as well... It's the hole size not the bullet diameter that matters. Rarely are they equal.
 
I measure from top of one hole to top of the farthest hole. Or side of one hole to side of farthest hole.

Top to top, side to side and center to center are all the same. Does not work well with one hole groups.
 
RangerPark said:
That's why I've been using the On Target calculator. All you need is a photo of your group and a reference length, usually the diameter of the target or size of the paper it's on. Fairly accurate as long as you take your picture at a right angle.
Click to expand...

Is there an Android app for that?
 
RangerPark said:
That's why I've been using the On Target calculator. All you need is a photo of your group and a reference length, usually the diameter of the target or size of the paper it's on. Fairly accurate as long as you take your picture at a right angle.
Click to expand...

I downloaded the free version and still new to using the program but I think it works great for my needs.
I noticed there isn't a preset distance for a 300M zero which I used to do a load test .The drop down list skips from 200M to 600M so I had to program it in using a 330 yard zero to get correct info.
I took a screenshot off my laptop as it is the only way I found to print off a paper copy with all the info from the program showing .
The 2.050 in written on the target was me doing a quick measurement with a set of calipers.
 
That's the one I've been using. The paid version has the option of merging groups together which helps for OCW testing. The free version does everything I need it to, even if it has some quirks and bugs. I find group offset vertical and horizontal very useful for fine tuning zero over longer distances.
 
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