As I previously posted regarding defending my apartment, I came to realize that penetration is a risk of injury to other tenants. So I've been considering using Glaser safety slugs, AKA frangible rounds. I understand that these are low penetrating, basically small buckshot rounds. My question is twofold: one, does caliber make a difference with frangibles (stupid question I know, but it matters as to my caliber choice), and will frangibles still reliably create a disabling wound? The low penetration is a double edged sword; on the one hand I need to penetrate enough to stop the bad guy, but not enough that I blow through three walls and possibly kill my neighbors. Age old bullet dilemma, I know. How much penetration is just enough for my needs? Forgive the ignorance of these questions. I've still not had any experience with handguns.