Ok guys, I'm fairly new to pistols and I am not really understanding some of the differences in calibers. Obviously .45 is bigger than .22, .357 is the same but longer than .38, etc.

My confusion comes in when you start to throw in 9mm, .380, etc. Where does a 9mm fall into place in terms of size and stopping power? What is the difference between a .38 and a .380? Any general terms or ways calibers are names that can help sort these types of things out, or is it just a matter of learning more about the various calibers?

Thanks guys!