I'm experimenting with a scoring program called On Target. It's kind of quirky and crashes frequently, but it has the capability to scan a target in high resolution and then, using a mouse, put markers precisely over a series of holes. The software will then give you the group size and other statistical data, allow you to store target data, etc.

With that program I get a 0.082" group size on the five shot target shown in my original post.

The question is, can I ever come close to reproducing that five shot group again? Probably not. In fact, the chances are between slim and none, but it will be fun trying.