[El Gato]

Any cartridge that is an effective man stopper will go through multiple walls.

Well, except for a 12 gauge loaded with bird shot. it'll go through a very near wall, but beyond that, it's not a good penetrator. I've seen several folks shot with it, but of course at 100 or more yards, not at "inside the house" range.

[El Gato]

Meant to add that I hope to never see anyone shot with a 12 gauge loaded with bird shot at “inside the house” range. I load mine with something a little heavier, but still not 00 buck. However I have brick veneer all around, and my neighbors do as well. Still, I don’t want that kind of mess to clean up unless it’s absolutely necessary.