I took your advice, Dave, and it worked like a charm. Like I had any doubt...
I was over on a Reloading group on Facebook, and saw someone with the exact same problem. He posted pics of his load in the cartridge gauge, and it's the same thing. I told him to expand the case mouth a little more, but he got 30+ comments telling him everything else to do. The most common bit of 'advice' was to purchase a Lee Bulge Buster.
I'm not familiar with the Bulge Buster, but I told him to try expanding the case mouth first, before spending any cash. I think he just ignored my advice. lol