Now another concern that always pops up is over penetration. People are worried that the more powerful guns are going to poke through more walls of their house, and potentially endanger their neighborhoods.
Here’s the thing. Remember good old Safety Rule #4. Be aware of your target and its environment? It still applies. You are responsible for where your bullets go, even in a gunfight.
And since you’re trying to stop somebody, any round powerful enough to poke a deep enough hole to reliably damage a person, is powerful enough to penetrate a bunch of building materials. TANSTAAFL. There ain’t no such thing as a free lunch.
But this is one benefit of using a rifle for home defense. Loaded with PROPER ammunition, the more powerful rifle bullet will often penetrate less than a pistol bullet. A proper defensive rifle bullet is going really fast, and is designed to fragment, which causes more damage to people, but also tends to cause the bullet to break in drywall and 2x4s faster than a slow moving, solidly-constructed pistol bullet. Either one will still penetrate, but with the correct ammo, the rifle bullet can give you the best of both worlds.
Carbine vs. Shotgun vs. Pistol for home defense « Monster Hunter Nation