Actually, to get back to the topic........... If living in Australia, if I could legally own a weapon, I would use it, if needed, for self, or family, preservation and take my chances in the courts later on.
It is a messed-up set of rules and regulations and red tape (mostly a bunch of bureaucratic BS) but in the end, ya gotta do for you and yours.
But that is just my OPINION and not advice....you gotta do your own thinking and considering on that one.