TR,
Not a bad looking Luger. I hope you will enjoy it. My advice to anyone wishing to get into this hobby is to buy books (and read them) before you invest in Lugers.
I agree with what others here have said, your pistol looks like a standard army issue BYF 42 Luger that someone somewhere at sometime replaced the center BYF marked toggle link with a Mauser Banner marked toggle link. Anyway, that’s the most likely explanation but perhaps not the only explanation.
Getting back to books, on page 140 of Jan Still’s “Third Reich Lugers and Their Accessories” the author lists and describes German Army Banners that are Banner Lugers with Army proofing. The author states that; “A very few Banner Lugers bear German Army acceptance stamps and were routed to the German Army. Almost all of these are dated 1940… “
A list of known examples follows and the author lists one 41 dated example (6683q) as a known 41 dated Army proofed Mauser Banner. If there exists a legitimate 41 date Army Mauser Banner who can say their never was a 42 dated Army Mauser Banner?
Is your pistol a legitimate 42 Mauser Banner Army? I don’t think so. The numbers on your Banner toggle don’t look right to me. Number ones on Lugers almost always are made of two lines with a serif on top as on your extractor.
But who is to say for certain when and where that Banner appeared on your pistol?
“There are more things in heaven and Earth, Horatio, than are dreamt of in your philosophy”. Buy books!