Originally Posted by Frito Bandido
Law enforcement officers are practically immune from prosecution if their errant rounds should strike an innocent bystander. If I shoot off a slug in my house and it flies out my house, into my neighbor's house and kills someone in there... guess what? I'm going to prison for a very long time. A police officer doesn't have to worry about that. It is completely sensible for a civilian facing the realities of the criminal justice system to choose a different load that will accomplish the objective of stopping a threat, but lessen the possibility of getting innocent people stuck in the crossfire.
You can't compare civilian home defense with police and military work. Very different animals.
As noted just below your post you can compare them. We like to use miltary and police style firearms and ammunition as well. Stopping a threat is #1.
Although it certainly is a lofty/thoughtful/intellectual exercise to worry about over penetration, it should not guide your decision. First of all, worry about practice, with practice, under stress, doing so one is much more likely to puts rounds on target. That helps stop a threat and also nearly eliminates the chance of any additional harm from over penetration. The relatively small reduction in over penetration from #4 buck compared to #1 or 00 just is not worth the reduced terminal ballistics. Certainly anything smaller than #4 buck is simply WRONG advice. #4 may be a reasonable compromise, but in my opinion the drawbacks are smaller than the gains.
Slugs are a entirely different game with regards to their penetration (massive to say the least). That being said slugs still can have a legitimate purpose in HD (engaging a target behind a wall or in some rare circumstances even in a vehicle).