I am honestly gobsmacked Steve, catapults are banned, yet I was looking at a compound bow the other day that can fire an arrow at over 300 feet per second that I (and my 12 year old daughter) could buy on the spot with no licence or even handing over ID. It's also bizarre as I am sure that if you look at importing them the import rules are that you can't import one with a wrist brace, but if it doesn't have a wrist brace it's ok, with no mention of individual states.
And yes Australia is harder on guns than the UK or US/Canada. For instance, you have to apply for a gun licence, which takes months to come through and needs the usual checks etc to be completed. However, when you have that licence, you still cant actually buy or own a gun If you want a gun (and i mean everytime you want to buy a gun) you then have to apply for a licence to acquire which has a "cooling off period". Which is utterly ridiculous as legally held firearms used in crime is a ridiculously low %, in fact I think you will find that there is a statistic like washing baskets statistically kill more people a year than legally held firearms.