This is my take on it:
Even if it were possible to ban or outlaw guns in the United States (it isn't) I don't believe that it would make things better. Because what you have then is a populace without firearms, a police force that do have guns but take time to respond, and the criminals that will still have guns because there will always be a source, legal or not. The big problem that I see is that a lot of guns in crimes aren't legal to begin with.
My opinion, cynical as it is, is that nothing will have changed, and in fact crime may get worse, and more serious.
EDIT:
Also, while it may seem annoying to others on here to see "non-Americans" spouting off about gun control, and anti-gun and what-have-you, you have to keep in mind that in other places, that is the norm. They don't have rampant firearms like we do here. The situation is different; the culture is different.
Likewise, the culture here is used to having firearms. It is so deeply set that it would be impossible to try to change now.