Yeah I've seen that phenomenon a few times, always with nickel plated brass, always Winchester. You have a couple of things you can do here.
One: pitch the cases (goes against the Scottish/Jewish in me)
Two: Warm up the case bases (I use a propane torch) just enough to melt the sealer/red gunk that is holding the primers in. Go easy with the torch! If the shiny silver of the cases discolors, you're waaay too hot. Then, with the cases still warm to hot, run 'em through your decapping die.
I have saved and reused a goodly number of cases doing it this way.
Regards,
Robert McNamera