Really? I'm pretty sure that anyone, who would actually kill another person, is not going to stop and say "Hey I really want to kill this person, but all I have is this knife. Oh well, guess I won't because it's not efficient enough."
There are a lot of problems in the USA, but guns really aren't one of them. There are major cultural issues causing the problems and people simply want a scapegoat for them. The nature of guns just make them an easy target.
I am generally in favor of less gun control, but I cannot disagree with hibikir on this point. The availability of guns, in many cases, leads to more crime and more deaths.
Say I want to kill someone. I'm 5'7", used to be 130 lbs (nevermind how much I weigh now, dammit). I have a knife. The guy I want to kill is 6'5" and weighs 250 lbs. If I bring a knife and engage this guy in a fight, there's a pretty decent chance, even if I manage to surprise him and stab him in the back or something, that he'll be able to overpower me. He might even disarm me and kill me with my own knife! Now, on the other hand, if I have a gun, I can just shoot him in the face. He's dead. Very little chance of something going wrong and me ending up dead instead. I don't know about you, but that would definitely make me think twice before killing someone if I didn't have access to a gun.
It's not just murders, either. I'd be more likely to rob a place if I had access to a gun. If you pull out a gun in a public place, and no one else has one, you can instantly threaten the lives of everyone in the room. You can't do the same thing with a knife -- everyone will just run out the door, because you can't kill them before they escape. One of them will grab his cell phone on his way out and call 911, and now you're screwed. You have much more control of a situation with a gun than you do with a knife.
Still, I think guns aren't the problem. The problem is that too many people have reason to commit crimes. We need to work on that, and in the meantime, let me carry a gun so I can protect myself against those people.
I'm surprised no one has really discussed the implications of gun ownership as a means of defense against a tyrranical government or an invading force.