what do different group shapes mean?
ex. if all shots are vertical, horizontal, triangle?
Everyone should know this. It's common knowledge...
A group that has horizontal distribution means that some of the bullets went left or right of the intended POA/POI.
While a group that's vertically distributed means that some went high or low of the intended POA/POI.
Actually, I read an article once where the guy was explaining how seating depth would cause the dispersion to change from horizontal to vertical and that there was a sweet spot just in between. But, I was never able to reproduce that exactly. ...just too many variables.