From what I've been able to find, Australia's gun laws enacted in 1996 haven't had much of an effect on violent crime. People can spin the numbers all they want, but one of the best summaries on the subject I've found is from author John Lott.
Here's a link to his very thorough blog post:
My overall position hasn't changed: If you don't like guns, fine, don't buy one. I can respect that. Just don't try to restrict my ability to protect myself and my family from violent attackers.