The most versatile hunting gun was invented many years ago by the Germans. It has two shotgun barrels in the standard side x side configuration, and a rifle barrel underneath. It is called a drilling ( German Drei = three) I have a couple of them. They are the ultimate! Consider this -
My Krieghoff is 16ga.x16ga. / 7x57R. The 16 ga. is often said to "carry like a 20, hit like a 12" It is choked IC and imp.mod, ( 1/4 & 3/4) which is about the most versatile choke combination for a double gun. The 7x57 is one of the smallest general purpose cartridges adequate for all hoofed game. It has an insert barrel in .22 RF Magnum that slips into the right barrel. The insert is accurate to within an inch at 50 yds and returns to zero when removed and re-installed. It has iron sights that fold away when shooting the shotgun and flip up automatically when the rifle barrel is selected. It has a 3-9 power scope in claw mounts which are instantly detatchable and return precisely to zero when clipped back on. It is light, handy, versatile, and capable of any hunting job I could ask within reason. But it is also a hand built work of art and very expensive! Sorry about that...