Direct pull Mauser-style air rifle (attrib. Büchel)

Direct pull bolt-action air rifle (attrib. Büchel) 

With thanks to Thoralf. He says:

"This one is shown in the Büchel catalogue from around 1910 and probably also made by Büchel because I have never seen it in a other catalogue. The gun is larger than the well-known Mauser style toy rifles from the same age and also quite powerful. All parts are marked with 40 [and there] is a Reichs Gebrauchsmuster stamp and a second number on the barrel. A third number is on the butt plate and [there are] cryptic markings on the fore sight."

This should be the [pistol version] of this gun:

https://forum.vintageairgunsgallery.com/rock-island-auctions/oscar-will-patent-air-pistol-etc/