He was a loner, with a clean-shaven face and wavy blond hair. His IQ was said to be 66. By all accounts, he was a terrible shot. But with the weapons he carried—the AR-15 and a second, self-loading military-style rifle—aim was almost immaterial. The SP1 could fire several rounds per second with little recoil. Pointing the gun at a crowd of tourists, it was hard not to hit somebody.

If all this sounds too horrifically familiar—an estranged loner, an AR-15, dozens dead in a matter of minutes—there is a remarkable twist to the story. In the wake of the Port Arthur massacre, Australian lawmakers did something about it.

Within just weeks of that tragedy, elected officials in each of Australia’s six states and two mainland territories—pressed forward by police chiefs across the continent and by the then-newly elected prime minister—banned semi-automatic and other military-style weapons across the country. The federal government of Australia prohibited their import, and lawmakers introduced a generous nationwide gun buyback program, funded with a Medicare tax, to encourage Australians to freely give up their assault-style weapons. Amazingly, many of them did. (Simon Chapman, an emeritus professor in public health at the University of Sydney, and an influential proponent of the original firearms legislation, has a very good summary here. You can also read his free ebook here.)

A land of roughneck pioneers and outback settlers, Australia had never embraced much government regulation and certainly not about their guns. This was a land of almost cartoonish toughness and self-reliance, home of Crocodile Dundee and Australian rules football. Here even the kangaroos box. But Port Arthur had followed too many prior deadly shooting sprees and Australians were clearly sick to death of them.

So what happened after the assault-weapon ban? Well therein lies the other half of the story twist noted above: Nothing.

Nothing, that is, in a good way.

Australian independence didn’t end. Tyranny didn’t come. Australians still hunted and explored and big-wave surfed to their hearts’ content. Their economy didn’t crash; Invaders never arrived. Violence, in many forms, went down across the country, not up. Somehow, lawmakers on either side of the gun debate managed to get along and legislate.

As for mass killings, there were no more. Not one in the past 22 years.

In 2002, a mentally impaired student at Monash University in Melbourne shot two people dead and injured five others. He came to his rampage with six handguns, not an assault rifle. Had he been carrying an AR-15, the toll would have been far worse. But even so, Australian lawmakers added a new National Handgun Agreement, a separate buyback act, and a reformulated gun trafficking policy to their legislative arsenal.

There has been no similar shooting spree since.

But it wasn’t just the murderous rampages that faded away. Gun violence in general declined over the following two decades to a nearly unimaginable degree. In 2014, the latest year for which final statistics are available, Australia’s murder rate fell to less than 1 killing per 100,000 people—a murder rate one-fifth the size of America’s.

Just 32 of those homicides—in a nation of 24 million people—were committed with guns. By comparison, more than 500 people were shot dead last year in the city of Chicago alone. (Chicago has about 2.7 million residents.)

Perhaps most remarkable is what happened with gun suicides in Australia in the wake of the post-Port Arthur firearm legislation. They dropped by some 80 percent, according to one analysis.

What stopped many of those would-be suicides—quite straightforwardly, it seems—was the lack of access to a gun, a generally immediate and effective method of killing. (Nine out of 10 suicide attempts with a firearm result in death, a far higher share than attempts by other methods.) Public health experts call such an effect “means restriction.” Some Australians found other ways to take their own lives—but for many, that acute moment of sadness and resolve passed in the absence of a gun.

Suicide “is commonly an impulsive act by a vulnerable individual,” explain E. Michael Lewiecki and Sara A. Miller in the American Journal of Public Health. “The impulsivity of suicide provides opportunities to reduce the risk of suicide by restricting access to lethal means.”

Which brings us back to the here and now. In 2015, an unthinkable 22,103 Americans shot themselves to death with a gun (see Table I-21)—accounting for just over half of the suicides in the country that year.

It isn’t hard to imagine what would happen without all those guns at the ready. In a world of raging hypotheticals, we actually have some good, hard answers for this. All we have to do is look down under. There are millions of American families begging us to do it.

Correction: This post has been updated to reflect the correct number of rounds fired by the AR-15.

This essay appears in today’s edition of the Fortune Brainstorm Health Daily. Get it delivered straight to your inbox.