Latest estimate, published last week, was 600,000 illegal firearms in Aus.

I think it would be higher. I have heard that there were 330,000 SKS/SKK rifles imported into Australia by the Hawke/Keating Labour Government, although no one seems to know the exact figure, in a trade deal with China in th late '80's early 90's. I was told by a Police Inspector that about 30,000 were handed in during the 'Buyback' (Steal-back) following the harsh gunlaws enacted after Port Arthur in 1996 after strong bullying/threats of the Australian states by then Prime Minister John Howard.

Seems criminals/terrorists have little issue with obtaining unregistered firearms.....