I have been shown round one hole groups that look like only one bullet went through them.

I have been shown oval one hole groups.

I have been shown elliptical one hole groups.

And I have been shown ragged one hole groups over twice the bullet diameter.

Eventually one wonders what qualifies as a one hole group for a three shot or five shot group. In some context, I wonder if a tenshot group is not easier to make a one hole ragged group than a five shot group...

SO what is a one hole group to you and why?

Kind of depends on the gun I'm shooting. A one hole group from a 94 Win is pretty much going to be a ragged multi caliber size hole (and a surprise) . A one hole group from a tuned br rifle I would expect to be one caliber or only slightly (less then 10% say) larger. Just my opinion tho', so we'll see what others chime in with. - Dan

I consider it a one hole group as long as all three or five shots touch each other. With Magnums I shoot three shot groups, with standard rifles I shoot five shot groups. I don't talk about a one hole group with any more shots than five. The bench rest boys strive for a single hole group, but I reload to be a better hunter of game and shoot some quite powerful rifles that I am tickled with if all shots are touching, not caring about the shape of the hole. My shooting buddy likes a three leaf clover hole, to me it doesn't matter. I figure if the holes are touching I have had a good day pulling the trigger. Good shooting.