[Bloody Sam Roberts]

If you live in an area where houses are close together or work in an office building where businesses are close together...a good choice is a 9mm semi-auto like the Ruger LC9 or a S&W .38 revolver.

Both loaded with frangible rounds. They pack a punch but dissipate their energy laterally very quickly. If you hit the target you do damage. If you miss, they won't penetrate the walls.

[VerySadAmerican]

I know a cop who shot a perp six times with a .38 at about 6 feet. Every shot hit the target. The 6th shot took him down. He lived.