Baldrick314 wrote:I've ran into some people who disagree and say you can't have a group smaller than your projectile size but as far as I'm aware centre to centre is the standard for measuring groups
They're not thinking about it in the right fashion.
Dustin,
If you're shooting 30 calibre bullets you're right, the hole in the paper will obviously be 0.30 inches.
For examples sake, if you shoot 3 bullets absolutely perfectly through the same hole, your group isn't 0.30 inches, it's 0.
Think of the centre of the hole as your point of measurement. If the centre of that bullets pass through perfectly overlapping the centre of the hole there is 0 spread, 0 variation, however you want to word it.
Like Baldrick said, centre to centre. In the above example the distance from centre to centre is 0.
If the centre of the bullet passes through 0.15" from the centre of the hole, your group is 0.15. That's how your group is "smaller than the bullet".
Make sense?