The re-emergence of gun control as an issue in the US has led to a fair bit of discussion of Australian experience. As is now normal on any issue, the political right has relied on Fox News factoids bearing no relation to the truth. But even for those seeking accurate information, it hasn’t been easy. AFAIK, there is no good place to go for an accurate summary of an issue that evolved in Australia over several decades. So, I’ll offer my own, based largely on recollection but with links where I can find them.
Although Australia has never had a gun culture on the scale of that in the US, gun ownership was widespread, with semi-automatic weapons becoming common in the 1970s and 1980s. There was also a vocal and effective gun lobby. Its first big win was in the 1988 New South Wales state election. The incumbent Labor Premier, who faced a likely defeat, rushed some restrictive gun laws through. The move was seen as opportunistic, and provoked a sharp backlash from pro-gun rural voters. This produced a perception, particularly on the conservative side of politics, that gun control was too dangerous to tackle. Despite a series of massacres, and rising rates of gun suicide, that perception endured until 1996 and the Port Arthur massacre.
The newly-elected conservative Prime Minister, John Howard, took a risk and pushed for nationwide legislation banning most semi-automatic weapons, and restricting gun ownership more generally. The package included a buyback of guns, on fairly generous terms, and tighter restrictions on gun ownership in general. Over subsequent years there has been some back and forth movement. The gun lobby, which has organized itself into a political party in some states, has nibbled away at restrictions whenever possible (their latest success was a proposal by the New South Wales state government, which needs their support, to allow hunting in national parks). On the other hand, as shooting incidents have exposed weaknesses in the law, they have been tightened up.
An important point, relevant to the US debate, is that the laws on semi-automatics worked without any real enforcement effort. I don’t think this is because Australians are more law-abiding than Americans. Weapons like these are very hard to conceal, so anyone who just ignores the law is taking a big risk – a disgruntled family member could turn you in, for example, or your house or car could be searched for some other reason. On the other hand, since much of the benefit of owning these weapons comes from showing them off, there’s not much benefit in having one concealed carefully enough to escape a search. It’s hard to figure out the thinking of the kind of person who commits a massacre, but apparently it doesn’t involve the years of advanced planning needed to acquire and conceal semi-automatics.
By contrast, although handgun ownership is tightly limited, criminals still have access to them, and they are used reasonably regularly in feuds between and within criminal gangs, though the numbers of such incidents are tiny by comparison with the US. Again, that’s not surprising, since handguns are much easier to conceal.
Coming to the results, Australia had fairly regular gun massacres before 1996. On the criterion of more than four deaths, there haven’t been any since. More generally, both gun homicides and gun suicides have declined substantially. But, as the career of John Lott has shown, with a finite data set, it’s always possible to find a statistical test that gives the answers you want. Lott’s counterparts in Australia are Jeanine Baker and Samara McPhedran, academics who are also active in the gun lobby. They make much of the point that gun deaths were declining before the ban, and have produced a series of papers claiming no significant effect. By contrast, suicides among young men nearly tripled over the decades leading up to the ban, and have declined since. In this case, Baker and McPhedran ignore the trend, and focus on an increase in suicides by hanging, which partially offset the decline in gun suicides. Their work is more thoroughly demolished here.
To sum up, gun control worked reasonably well, but not perfectly in Australia. The same would probably be true of the US.