(CNN) It doesn't have to be this way, President Barack Obama said.
"At some point, we as a country will have to reckon with the fact that this kind of mass violence does not happen in other advanced countries. It doesn't happen in other places with this kind of frequency. It is in our power to do something about it."
The U.S. has been shaken by multiple high-profile mass shootings in the past few years -- an elementary school in Connecticut, a movie theater in Colorado, two separate incidents at Fort Hood, Texas, and now the church shooting in Charleston, South Carolina.
But can something be done? Australia, a country that in some ways shares the United States' frontier mentality and history as part of the British empire, implemented sweeping gun-control measures that have been successful for nearly two decades. So, theoretically it's possible, but "the power to do something about it" in the U.S. is limited by factors that are deeply rooted in its culture and baked into its founding document.
Any change to the Second Amendment of the U.S. Constitution ("...the right to bear arms shall not be infringed") ultimately would require the approval of three-fourths (38) of the states -- forgetting the political hurdle of Congress' even proposing such a measure. The National Rifle Association, with more than 5 million members and a powerful lobbying arm in Washington, reflects a vast interest group in a nation where there are nearly as many firearms (more than 300 million) as there are people.
Gun control: Change is possible -- and fast
What happened in Australia? Gun violence was bad. A decade of gun massacres had seen more than 100 people shot dead. The last straw was an incident at a popular tourist spot at Port Arthur, Tasmania, in April 1996, when a lone gunman killed 20 people with his first 29 bullets, all in the space of 90 seconds. This "pathetic social misfit," to quote the judge in the case, achieved his final toll of 35 people dead and 18 seriously wounded by firing a military-style semiautomatic rifle.
What happened next? Only 12 days after the shootings, in John Howard's first major act of leadership and by far the most popular in his first year as Prime Minister, his government announced nationwide gun law reform.
Uniform legislation agreed to by all states and territories -- the national government has no control over gun ownership or use -- specifically addressed mass shootings: Rapid-fire rifles and shotguns were banned, gun owner licensing was tightened and remaining firearms were registered to uniform national standards.
How did Australia do it? In two nationwide, federally funded gun buybacks, plus large-scale voluntary surrenders and state gun amnesties both before and after Port Arthur, Australia collected and destroyed more than a million firearms, perhaps a third of the national stock, according to Professor Philip Alpers of the University of Sydney, who is editor of gunpolicy.org. No other nation had attempted anything on this scale. The national government also banned the importation of new automatic and semiautomatic weapons. And the buyback was paid for by a special one-off tax on all Australians.
What was the political fallout? It wasn't without cost to John Howard. Political interest groups among his conservative base raised hell, and the move met strong resistance from some in rural areas. His party's coalition partner in those areas suffered in subsequent elections. But the majority of Australians, shocked by the mass killing, backed action. And it worked. Multiple homicides involving gun are exceptionally rare, none have been remotely as bloody and random as the Port Arthur massacre, and none have involved the sort of weapons whose importation was banned.
What exactly happened to murder and mass killing?
In the years after the Port Arthur massacre, the risk of dying by gunshot in Australia fell by more than 50% -- and stayed there. A 2012 study by Andrew Leigh of Australian National University and Christine Neill of Wilfrid Laurier University also found the buyback led to a drop in firearm suicide rates of almost 80% in the following decade.
In the 19 years since the announcement of legislation specifically designed to reduce gun massacres, Australia has seen no mass shootings. As Howard wrote in an opinion piece for the New York Times in 2013, "Today, there is a wide consensus that our 1996 reforms not only reduced the gun-related homicide rate, but also the suicide rate."
Can America follow it? The gun culture in the United States is a powerful factor that can't be ignored. Howard acknowledged those key differences in an interview with CNN's Christiane Amanpour in 2013. "I don't come here with any lectures," he said. Australia started with a much lower gun death rate, he said, and "we don't have constitutional guarantees in relation to these things."
"However," he added, "that doesn't alter the fact that our murder rate using guns has fallen and there's not much doubt in my mind that it's the availability of guns that causes such a high rate of murder using weapons."