It's an odd problem. Some foreign-made brass is tight in the pockets, but you said you swaged these? Are you sure these weren't brass-plated steel cases that sprung back after swaging? I don't know why Winchester would have those unless they were made on contract overseas. A magnet will tell you.
If they are brass and not steel, my next step would be to run a primer pocket profiling reamer in and cut away the excess. If you have a Wilson case trimmer, their primer pocket profile cutters are excellent.
If the shell holder worked with most of the cases, that wouldn't seem to be the problem. You could buy a
primer pocket gauge to check, but unless you want to own the gauges anyway, it's not worth it for a dozen cases.