Bob
Would like to see photographs of the KM holster that this Luger came in. Reported 1938 dated Lugers near the serial number 9431i are mostly KM marked. I would speculate that your luger may have been one of those procured by the Kreigsmarine but not KM marked. More information in the link below.
PART 2/2. S/42-1938 LUGER, WITH ACCESSORIES Jan C Still
http://luger.gunboards.com/topic.asp?TOPIC_ID=7289
You made an outstanding find.
Jan