More than 1 million guns were destroyed in the aftermath of the massacre, but research shows Australians have restocked over the past 10 years, importing more than 1 million firearms.
Despite that, the number of gun-related deaths has halved since the gun buyback.
The University of Sydney study's findings will be used by the gun control task force set up by United States vice-president Joe Biden in the wake of the Sandy Hook school massacre.
Public health researcher Philip Alpers, who will be presenting the study at a summit, told ABC News 24 the task force has asked to learn about the Australian experience.
"Remember there were several massacres in Australia - Port Arthur wasn't the only one - and during the period that people were thinking about those massacres a total of a million guns were surrendered," he said.
"What's happened since then is that gun imports spiked while people replaced them, and then crashed again for several years and they were way down at lower levels.
"But then gradually for the past 10 years they've been creeping up again and Australia has now replaced that million guns."
Professor Alpers says the guns that have been imported are not the semi-automatics that were banned after Port Arthur.
"Remember that 90 per cent of gun deaths have nothing to do with mass killings," he said.
"They're actually suicides and domestic violence, and it only takes one bullet in a domestic violence incident.
"This is what the Americans are interested in - looking at this it's almost Australia has turned into a public health laboratory in terms of reducing gun violence."
He says it is too soon to judge the impact of the resurgence in Australian gun ownership.
"Guns are a bit like a virus," he said.
"You clamp down on one type of gun, another one pops up and you have to deal with that.
"So now we're faced with a slightly different problem - it may be a problem, it may be a serious one, it may not be too bad, but we have yet to see."
Mick Matheson from Sporting Shooter Magazine says more people are licensed shooters than in the past, which has made a big difference to the number of guns in Australia.
"The interesting thing is that at the same time gun crimes have still gone down," he said.
"We've got more shooters, we've got more firearms, but we've got fewer crimes.
"It highlights the fact that there's not necessarily a direct connection between how many shooters there are, how many guns there are, and the crimes that are committed out there."
He says a decrease in gun deaths after the buybacks may have other explanations.
"The figures did drop quite dramatically in that couple of years afterwards, but you have to look at the broader picture - they've been dropping for years before then," he said.
"Suicide by firearm had been dropping for more than 10 years before that period, and it continued to drop immediately afterwards, which counts for the biggest fall in firearms deaths. That corresponds with a massive public campaign about suicide and suicide prevention.
"The anti-gun lobby - and Philip Alpers is a part of that - has ignored a lot of these facts.
"That's really frustrating for a lot of shooters out there who are just trying to get out there and enjoy their shooting, their hunting, farmers who are just using their firearms as tools and yet we're facing this constant barrage from the anti-gun lobby."