"K" Date Markings
 

There are the following markings on my k date luger on the frame and under the trigger plate as follows: 929.7C.3569. the 929 appears to be put on with a graver, the letter c is upside down, and of course the characters are tiny in order to fit into such a confined space. Does any one know what if anything these numbers mean? All numbers otherwise match on the gun. Also while the k date and s 42 were disassembled for cleaning, it was noticed that the subinspectors marks were in different places on the guns, would it be worth noting and posting these differences on the site? Thanks for all your help, Bob

PS all of the numbers are stamped except 929.