This must be the disconnect with you, I suppose your books are not collector books based on observations, but rather historical books on people. That I can see, but a book on variations of Lugers would necessarily require observations and study of Lugers (or rifles if this is the case) bolstered by pieces of information from period documents. I can tell you now, not all production documents you see are 100% accurate either. Many of the documents relating to WW2 Rifles are forcasts, and I've seen people misread them.Yes. The reason we did our books was because we had direct access to original factory documents and with those involved in the entire process.
If I were you, I would contact the editors of Deutsches Waffenjournal (DWJ). Some of their staff managed to locate and interview the man who worked as a gunsmith's apprentice applying the DH markings. The man requested his identity to remain secret. But perhaps DWJ can provide you with more details.
However, there are no documents relating to SS rifles, yet collectors were able to figure out variants and authentication without those documents. It isn't difficult, and it isn't difficult to authenticate and root out fakes.
As to DWJ, they translated our first book into German and printed/sold it, perhaps I'll give my contact a call. Lets see if they have any documetation, I'll let you know - if not you might pull back on using that story in your lexicon of why these are fake.