Bill, I wouldn't worry. It seems to be a pretty poor repro, almost identical to those sold by Globe in the 1980s. I have never seen any oxidation on an original. You know, if this is new, I think someone reproed the repro that was being sold in Germany over the past several years as original. One was in a photo posted in a past thread and included the original document.

"This hobby is a continuing education"
Looking for Walther Model 8 #727649
and Walther PP #975557