Regarding shotgun wounding:

1 ounce of shot at a given velocity will have a given amount of kinetic energy. Birdshot will tend to dissipate more of that energy in the bad guy at 15 feet than buckshot,simply because there is less chance of the pellets exiting with any remaining energy, because the bird shot has a larger frontal area. But if you hit him in the chest, both are likely to kill him dead in very short order.The same is true of a handgun(of adequate caliber), or rifle. That same differential in surface area at impact reduces both the effectiveness on hardened targets, and the overpenetration risk in the event of a miss when using smaller shot. IMO (worth exactly what you're paying for it), 7 shot makes more sense in a home defense situation than 00 buckshot, simply because of the reduced distances involved. As far as shotgun vs. handgun, a 1 oz standard 12 guage load packs about 5 times as much energy at the muzzle as a 230gr .45 acp load. Add to that the longer sight radius, and for *most* folks, a shotgun is a more effective weapon under stress. Granted, some here have trained extensively with their handguns, and their mileage may vary.