I'm talking to a guy on FB that seems to have a unique Luger, but he (or I) aren't sure what variation it is.   He believes it was part of a Portuguese contract (not sure why he thinks that).  It has all of the features and markings of a 2 year digit 1942 byf marked Mauser (Black Widow) with a serial number of 3690n.  The thing that makes this Luger curious is the letter "S" stamped above the year. I can't find anything that would explain this mark.  I've attached a few pictures to show it.  Can anyone explain the S stamp?  What I can find of the Portuguese contract shows the Pistols were made in the "m" block.

Bump in Active Topics b/c Lugers are awesome.