Haenel Model XVa tinplate
With thanks to Robert S, Rafal, and Izabela for these pics.
Two more of this model, also in great condition, spotted on eGun.de:
An even better one here:
Haenel model XVa air rifle
Haenel Model XV tinplate
The model 15a without a fore end.
With thanks to Eberhard for the heads up.
Haenel Model XVa