Quite an assertion.
What Australia is doing works by one measure that matters: number of people killed by a gun. In 2024 the gun murder rates were:
US: 4.5 per 100,000
AU: 0.09 per 100,000
Ratio: 50
Source: https://www.ussc.edu.au/by-the-numbers-stark-contrast-in-aus...
Australia didn't confiscate vast numbers of guns by violence. It introduced a buyback scheme, which a lot of gun owners took up. The buyback was "an offer they couldn't refuse" for classes of firearms that were banned, but once it was done it meant it was more tractable to keep firearms in check. The big thing is did was reduce the number of households that contained a firearm even if some of the remaining (paranoid?) license holders increased their number of guns.
Source: https://www.sydney.edu.au/news-opinion/news/2021/04/28/new-g...