[Mauser720]

Yes, it does seem odd that Weiss never mentioned it.

Weiss was at DWM in 1929 and did not go to Mauser until 1930. Still reports these pistols were made in 1929 and 1930. So perhaps Weiss was not there when this project ("sneak" Lugers) started. ("Weimar And Early Nazi Lugers", Still, page 7)

Another thing that makes me wonder concerns Weiss's comment that "a few thousand" of these were made for the Riff Contract. If these pistols show up in the "s"; "t" and "u" serial range, you could in theory be talking about number up to 30,000 Lugers.