Well ,in light of the fact that you have just embarrassed a lot of us on here with that group Harold, I also will say nice shooting and congrats on finding a good load.
I've never been comfortable myself with trying to define the edge of the bullet holes and attempt my best to determine bullet centers of a group. But that's just the way I do it. Your extreme spread edge hole to edge of hole minus the bullet diameter works also... Once again, nice work....