Ed, are people returning fire? You getting shot at out there? If not, then just relax, brother. If it's not serious business out there, then don't make it serious business - it should be relaxing to go out and fire.
I did notice in your targets - DAMN! the horizontal spread was nil, but there was vertical stringing. That's most commonly from breathing. Do you remember how you were breathing when you shot that set of rounds?
This pic below, your right target - at 300 yards, there's not much more than one inch in the horizontal distance between those shots. Fucking impressive. The vertical spread - breathing, most likely. If you don't remember how you were breathing, then you don't have a pattern - that's my point. Shoot on the exhale. Breathe in, pause, breathe out, pause... Fire. Everytime. <thumbsup>