Been there, done that. If both rims exposed put one into shell holder in reloading press. Raise ram to get second rim exposed in top of press. Take a thin piece of metal and drill a hole or cut slot wide enough for cartridge case but narrow enough to support upside down shellholder so it can't be pulled into 7/8" die hole. Slip cartridge through hole or slot in metal and then slip loose shell holder over second rim and lower ram to separate.