DBax, I meant to tell you this earlier. I will show you my set up the next time I see you, but...
Forget a rifled shotgun. Forget a scope on the gun. If you don't have one already, get a very simple shotgun, in either 12-gauge or 20-gauge, in a smooth bore (full choke is fine). I would recommend you buy a used gun from a pawn shop or wherever, and make it into your Go-To slug gun.
Buy rifled slugs. Remember, rifled slugs go with smooth bore shotguns. WalMart sells these for $5 for a pack of 5. A pack of 5 will last you 2 or 3 years!
I have used a 12-gauge up until now, but switched over to a single shot 20-guage when I realized that was all that I needed. I have never taken a shot beyond 40 yards, so I don't need a scope. Bead sights, and game over.
Keep it very simple. And, the best thing is this: Very inexpensive set up, too.