Good to see your post, sorry I'm late to the party, LOL!!
I did a lot of tinkering with COAL in my Savage 12 VLP (.204) and really couldn't find one seating depth much better than another. I started at spec COAL, got my optimal charge, and then adjusted COAL around the charge. When I didn't get much reward by adjusting COAL, I stuck with the length that seemed to give me the best accuracy, and went back to tweaking powder.
When the the stars line up, I get .3" 5-shot @100, but That can easily go to 0.5". That's 32 VMAx's over 26.8 Benchmark, and my COAL 2.334"
I think we've batted this around before too, but it seems I've got to pump quite a few shots away before the groups tighten up, and they stay tight out to around 175 shots... that's how long I've gone experimenting with that thing (how many shots till accuracy comes/goes) anyway...