Did you size any nickle brass, or maybe a case with some embedded grit?
Home remedy I've used: Wrap an appropriately sized bore brush with steel wool, load it with JB bore compound, put it in a drill and give the die a polish.
Ditto
Probably some dirt or ? on cases when sized.
I have also used 600 grit wet/dry sandpaper wrapped on a dowel and a drill.Doesn't take much as you are taking off the scatch burrs above the surface of the die
