W. Voss may have been a stage name for H.Burgsmller:

W. Voss and Haselhorst & Co

http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=274106

Look at the very back of the frame, which should have a small extension and if that extension has a small screw, the sporting weapon would be of the Kerner-Anson design. If so, it would be a quality piece and fits the time period.

Kind Regards,

Raimey
rse