if your bullet leaves your property and hits someone

that's voluntary murder.

But in seriousness you're right, just like having an rpg for protection isn't really going to work.

In the house, you're actually probably better off with a barely legal length 12 guage shotgun with buckshot for almost all threats. Only exception is the worse case scenario I guess where a dozen people attack you at once and they're all armed. Then you just need a bomb keyed to go off if your heartbeat stops I guess.

Wasn't there a pistol grip short barrel shotgun called a "street sweeper" semi auto that held a dozen shells?

I understand now you can actually buy a magazine for a shotgun that is basicaly drum magazine and an adapter to plug into your shotgun that will hold 20 rounds?