In our new installment of "the truth about", I'd like to bring up home defense. Such things have been said as "shotguns don't penetrate as many walls as rifles", "handguns penetrate fewer walls than any long gun", and "rifle rounds will just keep going through walls". If you believe any of these, have a good read here:
http://how-i-did-it.org/drywall/index.html
TL;DR: three simulated walls (two 16x16 layers of 5/8" drywall spaced by 2x4s, which complies with building code) were set at range; 5, 15, and 25 feet. Fired at it were .223 varmint rounds, match rounds, and JSP, .45 FMJ, 9mm JHP, .380 FMJ, x39FMJ, and 00 Buckshot. Least penetration goes to the VMax, but varmint rounds also give insufficient penetration in gel, so they're not recommended. Runner up: .223 JSP (Winchester Ranger Power-Point), which bounced off the second wall. The bottom two? .45ACP FMJ and 00 buckshot, which sailed through all three walls unimpeded.
There you have it. The safest effective weapon for home defense is an AR firing .223 64gr. jacketed soft point ammunition.
I dunno about you guys, but this was pretty eye-opening to me. I've never seen anyone do a test that wasn't "eighteen layers of drywall all two inches from each other", which was a bullshit test from the get-go, and I'm really glad that this guy did what he did.
