There were changes in the 1990s - there was a big buyback which allowed people to get market value for firearms in a way they hadn't been able to before that, and a lot of people took advantage of it - most of the guns handed in were still legal, just excess to people's requirements - Americans seem to have been told that most of the guns handed in had been banned. That wasn't so. There were also efforts at the time to try and make inconsistent state laws more national. That succeeded to some extent at the time, but since then, a lot of that has actually been undone.
As I say, a lot of it is propaganda. It seems designed to make Americans think Australia did something dramatic in the late 1990s that made the country safer, and the US could do the same. Fact is, nothing particularly dramatic was done - and if Australia became safer, it's not because of those changes.
Is it true that self defense is not an acceptable reason for the authorities to allow citizens to possess a firearm?