The OP said one gun in the opening volley, and most opted for interesting rifle choices. A few went with the one "gun" and that one gun was a 12 gauge shotgun, a good choice to answer the question. But, in my world that one gun would be my fast twist .220 Swift. At 75, going on 76 years of age soon, my big game hunting is limited to deer and antelope. The Swift will take care of that with 75-80 grain bullets with the JLK my fovorite. When they run out, the rifle loves Bergers as well Barnes. Limited varmint and pest shooting takes up the rest of my time, and if a ruffed grouse is on the menu, the Swift can pick off a head as well as anything.
The number of available bullets for these chores is vast. There are at least some weights from 50 to 80 grain always on hand somewhere. Brass issues? Swift brass is like a lot of brass, tough to find. But when brass was starting to disappear of dealer shelves, I stocked up with more than enough to last me to my final day of pulling a trigger. And when paper punching comes into play, my Swift is fun to shoot off the bench. Shoot a barrel out? They make more blanks every day. Some talk about the Swift being a barrel burner, but I know of a lot of current popular cartridges that are a lot tougher on barrels that the Swift. In fact, with current steels used in barrels, short barrel life with the Swift is an old wives tale....