Hi,
Most of it would seem to be a "Precision" air rifle from the 1920s/30s. The "Precision" air rifle was made by Oscar Will who was later taken over by Wilhelm Foss, Venuswaffenwerk, Zelia-Mehlis, Thuringen, Germany. The reason I say most of it seems to be a "Precision" air rifle is that the one pictured in Hiller's Collectors Guide to Air Rifles, 4th edition has a different trigger guard and stock. If these have been replaced with parts from another gun and given the general condition I suspect it has little value but I have no knowledge of the survival rate of these and a poor example may attract a lot of interest if they are rare. Somebody will no doubt be along shortly with far more knowledge of this rifle.
atb
dogsbody