I'm absolutely the wrong guy to intercede with this post, but recently, when selling some modern firearms - I ran across a 42 byf RIG. My letter suffix is "f" and it appears yours is "k". Anyway - as a reference, Mr. Still in "Third Reich Lugers" (which I highly recommend if you do not have a copy) has some excellent photos and estimates that there were approximately 113,000 "42" byfs produced. Both the "f" and "k" block are included (mine and yours). While outside my collecting area - I do appreciate these Mauser produced Lugers. There is something about them
Anyway - here is a quick picture of mine. It's a RIG (holster - DLU 41 (Ewald Luneschloss, Militar-Effekten-Fabrik, Solingen, Nordrhein-Westfalen)) but neither MAG matches the overall serial number of 3063f.
Anyway - I hope this helps - and CONGRATS!!!
John D.