We tend to follow Victoria in traffic rules for some reason, and I think the powers that be do keep an eye on Aussie laws, we don't want a culture shock from all the to a fro-ing.
There are very definitely illegal guns in the criminal world, and in a previous life I have seen pistols and sawn offs in the hands of those on the otherside of the law. These are stolen, and they know where to steal them, it's not random. But not a problem to 99% of the population...in most cases of innocents in the way of guns the idiots doing a home invasion have got the wrong address, they should be next door.