Arizona shooting range accident

[Starter]

Mass shootings in Australia:
1984 - Milperra Masacre - 7 people
1987 - Hoddle Street massacre - 7 people
1987 - Queen Street massacre - 9 people
1990 - Surry Hills massacre - 5 people
1991 - Strathfield massacre - 7 people
1992 - Central Coast Massacre - 6 people
1996 - Port Arthur massacre - 35 people

1997 - $350m Federal Gun Buyback Scheme - 643,000 firearms were handed in
Number of shootings where more than 3 people have been shot in a single incident since: 0
Yes, it does shoot a big hole in the theory.

Namely, that the policy worked.

I could be mistaken, but I believe the discussion was about shootings in general and not specifically mass shootings. So cherry picking isn't helping your point.