It all depends on what you want to accomplish. In SitX self-defense, against a single person, daeoeste took my answer: Rock salt. You get multiple
penetrations of very sharp crystals, and every one of them feels like hell itself has hit them. But on the other hand, it's not (usually) lethal, so
if there's a court battle later on, you have the defense of not
shooting to kill, just due to the type of load. Yeah, he'll live, but
everyone who he tells will think a couple dozen times before playing with gunpowder-administered rock salt.
On the con side, you have to load them yourself (although anyone serious about shooting should have a reloader), and you better clean that barrel real
good after use. Rock salt is corrosive to steel as well as flesh.
Back to the shot size, it all depends on your situation. I'd recommend keeping a supply of #8 or #6 for small game hunting as well as scaring off the
average wanna-be looter. They do hurt, even if not as lethal as larger shot. You also want some #4 or #2 for larger game or for those who look to be a
little tough for the bird shot. Both of these are usually lethal, if not from the immediate damage, from the subsequent bleeding.
I try to keep a supply of 000 buck on hand as well. You have a better chance of hitting something vital/painful with shot and 000 is big enough that I
doubt the recipient is going to have much chance of not doing the bleeding to death quickly thingy. Slugs are also good, but don't expect them to
slam through things like an armor-piercing rifle round; they will stop soon enough, just not before blowing some really big holes in whatever was in
front of them.
It also matters whether you are using a full-choke or a modified choke shotgun (except for slugs of course). Full choke concentrates the shot over a
smaller area, so you can use smaller shot with the same results. You have to be a bit more precise on the aiming than with a modified choke,
Shotguns in general are great for fast shooting (aim is not as critical as a single round rifle) and for the fear factor (that hole in a 12-gage can
look huge when you're staring down it). But for immediate lethal damage or medium/long range, I'd take a rifle or good handgun any day. Less recoil
to allow you to re-aim quickly in changing conditions, more exact penetration, and handguns are easier to swing quickly and easier to hide than a big
edit to add:reply to post by mr-lizard
I don't think it's all that (although I will admit some people have that mindset), it's more a desire to be prepared in case of something. I have
plenty of firearms and other weapons, and all of them are there in the intense hope that they will never be used.
That said, I would rather have them and never need them, than need them and not have them. I have a responsibility to protect me and mine, and I have
no intentions of abrogating that responsibility to anyone else. The stakes are too high.
[edit on 27-9-2008 by TheRedneck]