Well Australia did have a US guns style policy up until the Unsworth NSW government became active in the heads of government.
Australian firearms were never "political" in the "Australian" community. They were pest control and wife shooters. They weren't connected to a narrative of political state creation. Australian militia were controversial but government run.
The political use of firearms in state creation was of course in massacre. But the structure of the frontier wars rapidly encouraged the concealment of massacre. And aboriginal resistance reconfigured itself based on passive resistance.
Current Australian firearm law is relatively open. The main costs are financial in terms of storage, certification, and the time to spend on range / pest control / hunting.
Port Arthur wasn't the tipping point, it was all the double and triple murser suicides from the 1970s long recession for the working class. Fixing international capitals returns to first world labour is an exercise left for the reader.
Yours
Sam R.