Howdy!
I am new to this forum and this subject matter.
My Brother was recently given a German double rifle. As I am regarded as the family "Gun Guy" he asked me for some help in identifying and possibly getting a value.

It has a large bore rifle barrel on the right side and a shotgun barrel on the left.

The only markings found so far are "o hellmann in heilbronn 10713".

I can't find any info on the Net.
I also have a few camera quality pictures.

Thanks!