Re: Velocity vs Accuracy?
Sounds like you have an idea of how this works, but check out Dan Newberry's page on Optimal Charge Weight (OCW) testing. It is a sound method of doing business and has never lead me astray.
Something else I didn't see you mention is your cleaning-cycle; are you doing all of your load testing within your cleaning-cycle both after the barrel is fouled in and before the copper takes a toll on your accuracy and gives you false POI's?
With that said, I like to think I have a firm grasp of how this works and am usually down at the Tacoma Sportsmen's Club (not too far from ya) on weekend mornings if you have any questions while you're sending them down range. Actually, I enjoy helping people working up loads so long as they have open minds.