https://www.rockislandauction.com/detail/70/2377

This unique custom sporting rifle (and shotgun) is a very cool example of the true gunsmith's art. This firearm began as a Mauser model 98 action, which was embellished and fitted with a fancy barrel (chambered for 8mm) and express sights. The gunsmith, Georg Knaak, of Berlin then added a 16ga shotgun barrel below the rifle barrel, on a pivoting mount that allows it to open to the right for loading and ejection. A second trigger and associated hammer mechanism allow the two barrels to be fired independently. The proof marks on the rifle section indicate that it was produced just prior to World War One.

http://www.patreon.com/ForgottenWeapons

Cool Forgotten Weapons merch! http://shop.bbtv.com/collections/forgotten-weapons