First off, this is NOT a poke at the OP.
When I see discussions concerning group size or group anomalies and everybody chimes in with excellent suggestions, I can't help but wonder why the first questions aren't about bench technique, setup, and weather/light/wind conditions. I guess we jump to the assumption that every Joe Shooter uses but the best gear, is a pro at reading conditions, and is a steely-eyed marksman who always puts every single shot exactly where it's meant to go.
Like I said, I'm not taking a poke at anybody. Just making kind of a philosophical observation about human nature.
