I would use my Pedersoli SxS 20 gauge with the left barrel with shot and the right barrel with a ball..., the left barrel is modified choke, the right is Improved Cylinder.
Now if I was going to buy a gun for the dual purpose, the folks are correct, you can use any number of rifles, and take head shots, or a good smoothbore, and have packets of shot and a bullet board standing by to add the projectiles that you need when you spot the game.
All of the above will work. :grin:
Is your shotgun an antique, or is it a repro that has worn out? I ask as just because it don't shoot, doesn't mean it isn't worth enough money to get you into a new gun or get you close.
LD