Help with magazine markings (new to the form)

[Mac Cat]

It's a beautiful Luger.
The matching magazines are really special.

I think it has been nicely refinished, because it has no signs of wear.
Your toggle where "byf" is stamped looks very scraped up and doesn't have beveled edges.
And, I agree that the suffix letter is an "X".

I have a 42 byf that looks very similar (below), except that it has holster rash on the muzzle,
the frame sides, the side plate and scrape marks from the thumb safety.