338 dude, thank you for the vote of confidence that I am not an idiot. However you might change your tune after I confess what was going wrong. I was improperly setting my bullet seating die and crushing the shoulder on the case. I realized when I switched to my 300WM in Norma brass, and the shoulder deformation was very pronounced. I switched back to my 7RM dies and loaded a round (with the seater die correctly set up) at 0.010" off the lands as measured with the OAL gauge, and sure enough it chambers and ejects no resistance.
Thank you for the help everybody, that was fairly embarrassing! Should I delete this thread, or might it be helpful for other first-time reloaders?