Yes, you need a current licence for a firearm matching the ammunition being purchased to legally purchase ammunition. The black market rate on even low calibre ammunition is rather prohibitive.
There's a whole chain of checks and balances to acquire a firearm licence including gun club membership and a sponsor, and therefore get access to ammunition.

In my 20 years in Australia I've been called up 4 times and been on a jury twice. Both trials were a mandatory life sentence if a guilty verdict was found. I have to say that I learnt a lot from the experience. I'd gladly do it again.
The two juries were both on the same 3 week period. We had just finished the first trial and got called in again for selection the next day, and were empanelled again within hours. Half the jury on my second trial had been in the first, so we were seasoned veterans by that point.