Although John's was a sideframe marking, it is kind of apples and oranges;
http://forum.lugerforum.com/showthre...threadid=17151
As Johns is a P code, and is in better shape. Not to say that "fenninger" 's is not valuable, I am sure it is.
I'd want it checked out by someone who knows Krieghoffs really well, that it matches, etc.
PS: Sn 22728 does NOT flow in the known serial numbers, even for "commericial" numbering..
Ed