+1 .450 N.E.

I've never hunted Africa or dangerous game animals. But if I was choosing a rifle based on your criteria I would go with .450 3-1/4". I have a single shot in that caliber and I really like the cartridge. I shoot Hornady factory loads out of it with wonderful results and I have no trouble getting the ammo. It does recoil but it feels like a lot less than the recoil of a 470NE. The .450 is the traditional standard to which the other big bores are compared.

BUT..... if I was to have only one double gun for small to medium to large thin skinned game minus elephant and buffalo to 100 yards then I would choose a 12 gauge Paradox gun.

"I have killed everything with it (12 bore 'Paradox') from tiger to snipe.--- E.H.R.H."
From Holland & Holland's catalog of 1910.