For all intents and purposes, YES Banned in International Post(Air). BY sea, is an unknown.
Cartridges of any Ball type(NO tracer/AP.Incendiary etc) can be brought in as personal Luggage by Air-travellers (Max. 5 kg) and of course in check-in luggage, but must be declared and cleared by Customs.
AS to “Inerts” that is a grey area…LIve Ammunition has to have a Permit from the Feds (A-G dept. Canberra) and also, if not part of a Visiting Hunter or Sportsman’s supply,( and travelling on his/her Rifle import permit,) also State Explosives Import Permit.
Again, the status of Inerts is unclear.
SO, in the long run, don’t think of it. WE do manage (Cartridge collectors) to get Bulked shipments from countries like NZ etc (following Auctions etc) but it is a long and confusing process.