Axel:
I could say the same of you for holding that a tubeset that experience preliminary proof pre-1910(also note the 1st set of "Eagle" "Crown/G" high on the tubes near the serial number & house number??) and then experienced final proof post 1912. I'm not living in the past hung up on some clown from the '60s, but other marks including length in mm, "Crown" over "N" and bullet type/bullet weight and their positions are typical of 1912 - 1924. Even in Mr. Cate's text I believe there was a DR with "181" stamps and powder charge over bullet type that he gives as post April 1912. In the post 1912 era there were other odd combinations. It is the bore stamp that is the culprit in the lot that is out of place in time. I'll gladly roll you high dice on this one and all this could be settled with a glance at the Sauer records. But if one holds to the reproof theory, I can't remember if there is a Nitro stamp on the frame, then your scenario is possible.

Kind Regards,

Raimey
rse