Time to sever the cultural link finally?
Gun culture came here with the Scotts-Irish, themselves brought here as prisoners back when the British Settlements in America also functioned as penal colonies.
That ended with the Revolution. And, you guessed it, subsequently started the wholesale colonization of Australia when Britain had no place left to throw the garbage out.
Yes, Australia was initially largely settled by the same generation spanning convict class that used to be cast away here. Difference is, while not perfect, they've been evolving past those roots whereas the USA has a booming population of stagnating fetid degenerate white trash more prone to gun and other violent crimes, drug use, perversity, less education, lower IQ's, higher breeding rates, and other fine qualities that make the US a joke amongst more advanced nations, an advancement that we birthed, btw.
Get these people to join their more civilized cousins, and their propensity towards such behavior begins to decline.