I think your headed in the right direction Prairie Boy. Looks like you've already did some research into the subject. Theres some work being done with the 300-.338 ultra but I haven't seen to much info on the results yet. I personaly went with the .338 ultra, 28' Krieger barrel on a blueprinted Rem action. Haven't had a chance to let her "reach out and touch" yet. Looks good out to 400yrds. Good Luck!