NitroX:
When you contact the "transporting guns" guy at Qantas (?), to get the letter of authority to transport firearms and ammunition, get him to include the cartridges and specify a packaging standard with which your reloads can comply.

It is a very good idea to get this letter, in fact I would regard it as mandatory, because so many counter-staff are simply not trained in how to process firearms and ammunition. If you present the letter on their own letterhead, they can't argue, or interpret the regs their own way.

I would strongly advise against transporting ammunition in a cartridge-belt or belt-pouch, it could be interpreted as being "ready for action" by the afore-mentioned untrained staff!

If you are flying Virgin, or Slut (Jetstar), I don't know the requirements, although I'm sure other posters here can advise.