You seem to have a stalking rifle with a Roux action. It appears to have been proofed in 1933 for a lead 170 grain bullet. The cartridge is likely the 8.15x46R for which components are still available. Slugging the barrel and doing a chamber cast will tell for sure. The BUG proof marks are the usual for a gun with a rifled barrel. The logo is of the maker, Bernhardt Paatz of Zella-Mehlis. The company was founded in 1890 and continued until WWII.
We don't have anything useful. I looked to see if anyone reprinted any of their catalogs or if the Deutsche Waffen Journal might have an article on him. No luck. We have had inquiries about Paatz but mostly about the 22lr's that the firm made. One of our member's father worked in the plant during WWII but they were making aircraft parts then.