How do you measure group size??

I use the good ol' fashioned eye test! I don't feel the need to pin it down to thousandths of an inch - I'm not a good enough shot to get a group worthy of that level of scrutiny anyway. Most of the time, I'm just hoping they all get on paper!

If I was, it seems to me like drawing a circle around them and measuring the radius gives you the most valuable information. But maybe for precision stuff measuring from the center makes the most sense.

Center to center

I just go buy how well they group. I never measured them.

I zero the caliper at the bullet diameter then measure the max spread from outside edge to outside edge. The edge of the hole is easier for me to locate than the center

Zero on hole diameter, then go outer edge to outer edge.

Or use an app.

I too use the outer edge, in determining the MOA, much easier than locating the center of each hole.

Max spread minus diameter of a bullet
if it's a 6mm....and outer diameter is 1"
1.000"-.243"= .757"

If 5 don’t clover leaf I don’t check by size.

Just kidding if my closed hand covers the group that’s good enough for my purposes.

Don't measure---shoot at a 2in circle---if all my holes are inside or touch it I am happy.

For those measuring outside to outside and subtracting a bullet diameter, most likely your calculation isn’t actually yielding a center to center equivalent - shoot a single bullet hole into your paper sometime and measure it. Pretty common for bullet holes to be considerably smaller than the bullet diameter, so subtracting the bullet diameter instead of the HOLE diameter undersizes the actual group measurement.

Well, I subtract the bullet diameter,.... and any flyers

Outer edge to outer edge of two widest two minus one bullet diameter. Gives you c-t-c.
Interesting thought, if your gun will shoot two inches, it'll be within an inch of center

Varminterror said:

For those measuring outside to outside and subtracting a bullet diameter - shoot a single bullet hole into your paper sometime and measure it. Pretty common for bullet holes to be considerably smaller than the bullet diameter, so subtracting the bullet diameter instead of the HOLE diameter undersizes the actual group measurement.

Click to expand...

learned something new...just did this and my group size got bigger by .008

JDGray said:

Center to center

Click to expand...

This is what we do in the long range IBS.
Calibers may change but the center is always the center

Honestly—

Hitting a plastic orange juice bottle, mostly at 25 yards (Action Pistol), sometimes at 50 yards.
-The bottle jumps into the air- A VZ-58 (true Czech) and three imported AKMs 'motivate' the bottles.

Not kidding. It’s only about having fun. Iron sights only.
Very seldom have anybody with whom to shoot anyway.

PS: A VZ-58, and some of the better AKMs (out there) can achieve - with red dot scopes etc - 1.64 MOA, at least for several shots, if not more. Not Chris Kyle potential, but a pretty small 'barn door'.

"Rob Ski" with AKOU, on Youtube, in one of his VZ-58 videos.

Minute Of Pop Bottle ?

Download a group measuring app on your phone. Much easier. You just need a reference in the picture that you know the size of. Then use the correct diameter bullet model and outline the holes.

Screenshot_20210329-141840_Range Buddy by chase, on Flickr

20200301_140051 by chase, on Flickr

I measure from the near side of one hole to the far side of the next. That way I don't have to worry about bullet or hole size or guess where the center of a hole is.

Identify the 2 bullet holes the greatest distance apart. Measure from the inside edge of one to the outside edge of the other. Far more accurate than trying to eyeball the center of the holes. Technically you measure from outside to outside then subtract bullet diameter. For example if the outside spread is 1.023 and I'm shooting a .308, then 1.023-.308=.715" group. But to within the closest 1/8" is close enough for my purposes.

Center of the two holes farthest apart.

I don’t measure. I eyeball it and tell everyone it’s sub MOA

Interesting. I usually measure either edge to edge or center to center .Close enough for me but I could benefit from the phone app. Especially reporting on groups.

I measure them the opposite way I measure fish. I don't call it lying, just consider it adjusting reality.
Hold fish as close to the camera as possible, targets as far away as you can get and still see holes.