Manteuffel air rifle (post-WW2, Geco brand)

Manteuffel air rifle (post-WW2, Geco brand) 

With thanks to Eberhard.

He says:

Probably initially produced after the war in the Soviet occupation zone by ‘MAN-Teufel’ as mod.10 for export to Sweden under the GECO brand name. Certainly also with pre-war parts from the Favorit I + Haenel 45.