Actually in response to the individuals stating the Australian gun laws did not work please see this article. John Howard is not a liberal he is a conservative and I watched his interview about a month or so ago and he claimed that the guns laws did what they were intended for and more.
http://www.washingtonpost.com/blogs/wonkblog/wp/2012/08/02/did-gun-control-work-in-australia/
/Given those flaws in the studies showing no effect, the Leigh and Neill study appears the most reliable of the ones conducted. It seems reasonably clear, then, that the gun buyback led to a large decline in suicides, and weaker but real evidence that it reduced homicides as well. Such a buyback isn’t in the cards in the U.S. anytime soon — an equivalent buyback here would entail the destruction of 40 million guns — but the data suggest Howard might have a case.