Unless you're like some of these other folks on here who seem to think they have 40 yard hallways in their homes, that 7 1/2 shot will do some serious damage.
Deadly force self defense situations mean the guy's in the room with you or across a room at most. #7 1/2 shot at 15 feet will punch a hole the size of a baseball and penetrate more than seven inches into flesh. Of course, to hear some folks tell it, the only person you'll ever have to shoot will be superhuman, armored, on drugs, inhabited by aliens yadda yadda yadda so a cannon wouldn't hurt them.
If you want to be creative, open the tops of a few, drizzle liquid paraffin/wax down into the shot, and then use a Lee Loadall to recrimp them. Makes basically the same ammo that the military and the law use to breach doors. It will punch a hole you won't want to look at afterward.