When asked about gun control laws I find myself invariably turning to one of the best quotes on the subject I have come across:

"Criminals don't obey the law. It's more or less a requirement for the job."

In short, by forcing everyone to turn in guns, all you are doing is preventing good honest, law ibiding citizens from protecting themselves, as people in heavily gun-controlled countries will probably tell you. What's more, even if you do somehow manage to keep guns out of the hands of criminals, you still wind up with the same problem. Knives are the fallback weapon of choice for the main criminal element, and unlike a firearm, the power of a knife is directly related to the strength of the one wielding it. The Colt .45 wasn't called "The Equalizer" for nothing. The fact that it is easy for anyone to kill someone with a firearm is precisely the reason why they are necessary. Even a little old lady can take out someone breaking into her house. Criminals are a lot less likely to rob, rape, or otherwise harm others if they know that there's a good chance that they will get their heads blown off by the handgun that their target has with them.