Hello Tac..!
Actually - there are two instances requesting serial numbers. Personally, for Kriegs - I keep a confidential database of the numbers.
As well, Ed T. began a project that is quite useful, which are photos of the serial numbers with letter suffixes from various periods and manufacturers. Folks can send their photos to either myself or Ed or John S., and we'll include them, but without attribution to the owner, should they want to remain anonymous. That example of work can be seen here:
http://www.lugerforum.com/Suffixes/Suffixes.htm - and as you can tell, are far better then the "hand drawn" examples noted elswhere in the Lugerfoum technical area.
In either case, serial numbers and suffix photos would be simply terrific, even if the Luger is deactivated.
My Best to you always, Tac!
John D.