The ban on over-.38 calibre handguns in Australia only affects certain disciplines of sport-shooting at a pistol range. IPSC was the worst affected, though Service Pistol and Action Match suffered too.

For occupational use, such as safari guide, pastoralist, professional fisherman or environmental surveyor, any calibre you like. Any legal 'hunting' would have fallen under one of these categories anyway.

The .45 ACP is a bit dismal as a hunting cartridge IMO, and will always be a distant third behind the .44 Magnum and .45 Colt for general field work.