[mrerick]

Hi Paul, and welcome to the forum.

These tooling marks help provide some insight into the type of milling tools used to broach out the interior of the frame's forging, as well as the sequence that the tools were used in.

There is enough difference between the different manufacturers that you can clearly see which factory and process sequence made the frame. The small letters, numbers and symbols are individual departmental worker inspection marks used to confirm completion of each of the sequence of processes within the factory that made the gun. Those process documents are no longer available so we don't know which individual was associated with a particular marking or even which process was gauged, inspected and verified as completed.

These factory processes were, of course, documented by companies like Mauser that made your Luger. Some of that original material surfaces periodically.