[Three-Five-Seven]

Extreme spread tells the story as well as, if not better than, standard deviation. An outlier will change SD but a little bit. However, an outlier will also loose a big match. So, for our purposes, extreme spread is probably a better metric.

It is a simple matter to detect the fastest and slowest rounds in a group and to subtract the latter from the former. If extreme spread is single digits, you've done all you can to maximize ballistic consistency.