it seems that a ppk can rust very easily. I had one (1964 7.65mm import) in a case that must have had some moisture in it for a week and found some rust on the frame around the grips. Well the rust marks came off but so did the bluing. Just a little silver showing on the frame under the trigger guard between the grip plastic but it made me sick as this was a very clean gun. And I had had it only two months.