Shot gun is the only choice for a one gun "only" for deer and ducks, rabbits, dove, etc. Look into Mossberg 500 Field/Deer combo. You get a smooth bore shot barrel and rifled barrel. For deer and hogs, a rifled barrel and quality sabot ammo should be good out of this pump action out to 125-150 yards or so. Expect groups of aobut 3" at 100 yards.
If you stay with a smooth bore barrel only, it'll be less expensive. And rifled slugs are available. But in general these neither group as well, nor are they effective nearly as far out as the sabot slugs out of a rifled barrel. (Probably to the tune of 50 yards less). Sabot slugs in a smooth bore don't get it. The slug comes out not spinning and will never stabilize. It'll be a guess where it will hit.