Jello wrote:
Umm... what kind of wall isn't a .45 ACP going to penetrate? Cinder block?

Well, if you're firing stray shots that directly hit the walls, that's a problem with just about any handgun caliber and normal walls. If you hit your intended target (typically, that would be at point blank range), a .45ACP is unlikely (perhaps I should say "less likely") to keep going through other things, as compared to a .357, .44. .50, etc. or any centerfire rifle caliber. A shotgun using birdshot is even better (but it might not stop the intruder).

RE: Guns for Safety? Dream On, Scalia. - washingtonpost.com