How do YOU measure shot groups?

[cdr4thBn]

Yesterday a bunch of us where sitting around watching two football games on TV so the conversation had, of course, turned to hunting.......shooting to be more exact.
We had a difference of opinion as to how to measure shot groups. Without any prompting or discussion I' ll ask how you measure shot groups? Does anyone know the " official" way to do it?
Don' t be shy to answer just because there' s a bet on it.

[charlie brown]

Shot groups should be measured center to center. I measure from one outside edge to the same outside edge on the farthest hole away from the first hole, not all the way across both holes. Its the same as measuring from center to center.

[stubblejumper]

If the holes overlap measure outside to outside of the holes farthest apart and subtract one bullet diameter.I use all shots fired in every group and do not delete any called flyers.When you average out several groups a single flyer has little effect.I quote a guns accuracy by the average of several groups not by the best group fired.A gun that averages 1/2" for several groups deserves to be called a 1/2" gun.A gun that fires a single 1/2" group but averages 1" when all groups are taken into account is a 1" gun to me.Using this criteria there are not nearly as many 1/2" hunting rifles as one would be led to believe.

[westbronco]

Many people make the mistake of measuring the two shots furthest apart and calling that the group size. If you shoot three shots equilaterally spaced, you haven' t got the diameter of the group that way. You have to include all of the shots for the group. I have had good luck using a draftsman' s circle template which has a series of accurate holes that go quite large depending on the template. By finding the hole in the template that just encloses all of the bullet holes and then subtracting the bullet dia., you have a very accurate group size measurement. These templates can be found in office supply stores for just a few dollars. Hope that answers the question.

[Vapodog]

I use a hole template used by drafts people. It has holes from 3/8 to 1.50 in 1/16 increments. Center to center

[Mykey]

I agree with Charlie if and when i measure a group. I don' t worry about measuring groups that much though if i get a tight group then i just load. The targets i use have 1" squares and if i have a three shot group inside those squares or have a couple just outside the squares from a 5 shot group then i' m happy because for me thats fine for hunting.

[noway]

There are two methods, you need to use.

For groups where the bullets are all in one ragged hole you have to measure the group outside edge to outside edge. Then subtract one bullet diameter.

Far larger groups with individual bullet holes it is quicker to just measure center of hole to center of hole on the two bullet holes farthest apart.

[BarnesX.308]

The way I shoot, I measure my groups in feet

[mainehunt]

I' m not saying that I am correct, BUT.......I always measure center to center of the two holes that are the farthest apart. I don' t know anyone, personally, that does it any differently.

[Troy R]

The correct way to measure like noted above is to measure outside to outside of the two fathest bullets apart from each other, then subtract that by the bullet hole Dia. The bullet hole Dia. is not hte same as the actuall bullet Dia. Lets say you are shooting a 22-250, the caliber is a .22, but 9 times out of 10 the bullet hole will measure .20 on paper.
So the correct way to get this is to take your paper target down then lay face down on something hard and push back the tore paper that has been pushed through, try ing to fill the hole back. Then you measure the bullet hole" you might measure 2 bullet holes, then measure the outside to outside of the furthest holes and subtract the bullet hole Dia number you got from measuring off the hole itself and there is your group.
When measuring the bullet holes you include measuring the black around the hole, that is what the bullet did going through.


Troy