Hi ZeroX:
The three primary gun "disciplines" are the rifle, shotgun and handgun. Each is for different sorts of things, and each in turn can be divided between "sporting interest" and personal/community defense.
The latter are NOT "inherently evil". Don't let anybody try and convince you otherwise.
I'm going to assume for a sec you're interested in the defensive side.
First, let's talk morality a sec.
Go here, and look up the polling data:
http://www.thehighroad.org/showthread.php?s=&threadid=84399
Note the high percentage of Libertarians around here...and many others who aren't registered with the actual political party "lean that way", myself included.
There's a reason for this. The core "Libertarian" belief is that the only crime (or "sin") is to initiate force against another person. "Force" includes murder, assault, rape, theft, fraud, etc. Someone committed to this "zero aggression principle" will RESPOND to violence but never initiate it...a genuine follower of this code is extremely trustworthy with weapons.
Next, you also have to understand your state's laws on the use of deadly force. The exact rules vary a bit between states. In my state, California, you can use deadly force to defend yourself or others from criminal assault if someone's life is in danger or they're in danger of suffering "great bodily injury". That part is pretty common. Some states have a "duty to retreat where possible" clause, which sometimes only applies on the street or can even apply inside your own home.
You need to know these rules. Any better gun shop in your state will have handbooks on sale specific to your state's gun laws AND "deadly force laws". You *need* that book, BAD. OK?
'Cuz the consequences for screwing this up are really seriously out-there bad.
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Right, 'nuff o' that.
Revolvers have some basic advantages over semi-autos. They're more accurate for the money spent (except in 22LR caliber), and more reliable.
All "calibers" are actually a complete specification for a bullet. "22LR" is short for "22 Long Rifle". "22" is the width of the bullet while "long rifle" is the particular type...which means a certain size case and a certain maximum power. Which considering the spec dates back to the late 1800s isn't real hot at all (despite the "fierce" name). The more modern "22Magnum" is much hotter, for example...but 22LR ammo is DIRT cheap. About $12 gets you 500 rounds. Some of the cheapest "serious ammo" you can get, 9mm or 38Special, will still run about $8 a box o' 50.
So a lot of us will have a 22LR handgun laying around for cheap practice even if we use hotter stuff for everything else.
Revolvers are sorta mechanically complex, and can get screwed up sometimes. There's a HUGE discussion thread going on how to pick out a good used specimen over here:
http://www.thehighroad.org/showthread.php?s=&threadid=1430