Here in Queensland, a 50 BMG rifle (even bolt action) is in the same weapons licence category as machine guns, grenades and rocket launchers (category R) ie hard for the average person to obtain. There is a necked down version of the 50 cal (460?) that can be purchased on a. more conventional, category B weapons licence (centrefire rifles). Once you have one, shooting these rifles requires a range with a long safety template and many ranges around here can't provide this. Ranges have to police approved and safety template is the major factor in the assessment.

I've heard rumours that it will also become difficult here in QLD to purchase a 338Lapua/tactical long range rifle, not so much from being made banned, or shifted to a more restricted licence category, but by the Weapon's Branch assesssing officer denying a Permit To Acquire. Allowing the PTA has always been at the discretion of the assessing officer (this is also true in WA where their equivalent of the PTA is handled by their Firearms Branch). I'm not aware of any such PTA being denied however.