Group measuring

[Deton8tor]

I am new to the site and new to L/R, compet. shooting. I have a question which I am sure has been debated more than once. But, what is the correct way to measure a group? Center to center or overall size etc. All reply's welcome.

 

[fivering]

Center to center of the widest shots.

 

[bozo699]

fivering is right but if you want to be exact measure outside to outside with a good pair of calipers then deduct the diameter of one bullet. example,

Group .500 outside to outside - .308 bullet diameter = .192 group size

P.S Welcome to the forum, and good luck.
Wayne.

 

[SS427]

For a truly accurate measurement, I measure the size of a single bullet hole and use that to subtract from the outside to outside measurement. (If I blow the group, with one bullet hole standing alone, you can measure from the inside of that hole to the outside of the farthest hole away.....no math involved.)

For instance my .224 caliber bullets leave a hole in the paper about .210 in size. My .243 caliber bullets leave a hole about .225 in size. I use card stock for my targets, so the size of hole your bullet leaves in the paper might vary. I find if I subtract the actual caliber size the group measures smaller than it really is.

 

[bozo699]

Otter,
I never checked that out before, good point, I will measure a bullet hole in one of my targets tomorrow and see what it measures I just use 8x11 printing paper unless I am trying to showoff or sell somthing then I use what I think you were talking about,white paper about as heavy as a cereal box? anyway thanks for the info Otter.
Wayne.

 

[Old Navy]

I turn my targets over, push the ragged edges back in place and put a piece of Scotch tape over the group. When you turn it back over you have holes that are perfectly round,black and the right diameter. Very easy to measure. Later! Frank

 

[Steve Blair]

If you own or have access to a scanner, OnTarget software will use the scanned image to measure groups very accurately as well as supply some useful statistics. The images can be stored for later reference and the paper discarded.