Here's an image from a 1920s(I think) Brenneke catalogue of the Musselshell lockup and following are proofmark pics of Mark Baumgarten's Brenneke safety drilling with Poldi tubes. There's an article in GGCA publication No. 22(Summer 2004) detailing Mark's father and the receiver.

Anyone know what currency units the "Cr. 1000" might be?

Interesting that some function of the tube making was performed by Valentin Christoph Schilling on this Suhl made drilling. I wonder if ole Konrad Heym was still involved. The rifled tube at 65cm is a good deal shorter than the 72cm scattergun tubes.
Robert Schrader of Göttingen(founded firm 1885) had a patent on September 10, 1902 for drillings with rifled tubes of lengths 40 - 50cm and scattergun tubes near 72cm(I'd like to see the patent to see the actual range). Robert Schrader had several patents and his drillings were complex with odd features similar to Brenneke's. Baron von Münchhausen was a client of Robert Schrader's and was a fan of the 40-50cm rifled tube on a drilling. Schrader more than likely sourced the craftsmen of Suhl.
Kind Regards,
Raimey
rse