I have a Remington Marine Magnum that holds 6+1. I don't leave it chambered so hat leaves me with 6. I am also of the thought that if 6 rounds won't do the trick, more rounds won't help. I keep a handgun nearby with extra mags so I'm not overly concerned.
The shot gun is more for the "safe room". I would grab the pistol and get everyone in the safe room. Then cover the door with the shot gun. If anyone comes through the door, they are going to get some buck shot in the chest (unless we get invaded by midgets... Then it might be a head shot or even miss them!).
