The tubes were probably proved separately at an earlier time and then the whole lot was proved in 1931. How do the German Imperial Eagles of the tubes and flat compare? Are they similar or is the one on the tubes more close knit and the one on the flats has more air between its components.

There should be some initials near the forend lug and somewhere on the tubes. I expect one of the letters to be a gothic "J". It will have Krupp steel tubes, but is the type stamped?

Roundtop: I'll have to download it again but if it doesn't have a sharp transition at the top of the frame, then the only other choice is a roundtop.

Kind Regards,

Raimey
rse