Hello Thor,
This won't answer your question but it may help. The image is a paragraph from an aricle written in the 30th Edition, 1976 Gun Digest by Robert A. Burmeister. It is quite interesting in that he feels the Mauser military lugers (reproductions) were much superior to the earlier lugers in regards to their metallurgy. This may be why you are experiencing what you have noticed in the K-Date. I thought you would be interested.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
Regards,