It's been 20 years since Australia rolled out nation-wide gun law reform. And now an analysis of more than four decades of data on violence in the country has come up with a conclusion: it worked.

The study found there have been no fatal mass shootings since April 1996 - despite experiencing one every two to three years in the decades leading up to the changes. There's also been an overall drop in the number of people killed by guns.

"If you take away the means of committing a mass killing with firearms, you don't have mass killings for the next 20 years," lead researcher Simon Chapman from the University of Sydney told ABC. "That's been our experience here [in Australia]."

The results come at a time when the US is reeling after its most deadly mass shooting ever, and experts are predicting that around 30,000 people will be killed - or kill themselves - with guns in the country this year.

But last week, the US Senate rejected four proposals to tighten gun laws, amid arguments that gun control takes away personal freedoms, and won't necessarily stop humans from killing each other.

To figure out whether or not that was the case, a team of Australian researchers looked at government stats on gun deaths between 1979 and 2013, as well as media reports of mass shootings - which is classified as an event where five or more people are killed by gunshot wounds.

The researchers found that there had been 13 fatal mass shootings in the 18 years prior to the new laws being rolled out, killing 104 people. But in the 20 years since, there have been none.

And while the rate of total firearm deaths was already in decline before the gun control reform, since then, it's dropped almost twice as fast. Gun-related suicides have followed a similar trend.

"Opponents of public health measures to reduce the availability of firearms often claim that 'killers just find another way'," said one of the researchers, Philip Alpers. "Our findings show the opposite: there is no evidence of murderers moving to other methods, and the same is true of suicide."

Australia first introduced its gun laws following a tragic mass shooting in Port Arthur, Tasmania, in April 1996, when a man used two semiautomatic rifles to kill 35 people, and wound a further 19.

The government responded quickly - less than three months after the event, Australia had banned all rapid-fire long guns, including those that were already privately owned, and introduced strict punishments for anyone caught in possession of the weapons - including jail time.

To further encourage gun owners to give up their existing weapons, the government bought back all the outlawed guns at market price, no questions asked.

In 2003, the federal government also began buying back handguns - and since 1996, more than a million privately owned weapons have been surrendered or seized, before being melted down for metal. Overall, gun ownership has declined by 75 percent in the country between 1988 and 2005.

But many opponents of gun control argue that Australia was already a safe place, and that these gun laws didn't have any significant effect on gun violence in the decades that followed.

While past studies have failed to draw any definite conclusions, this latest research demonstrates for the first time that the gun control laws did reduce deaths.

Here are some of the key findings from the study:

Between 1979 and 1996, total firearm deaths in Australia were dropping an average of 3 percent each year. In the 20 years since, they've declined at a rate of 5 percent annually.

There was also an acceleration in the decline of both gun-related suicides and homicides following the new laws.

The researchers also looked at the rates of all causes of suicide and homicide, to get a feeling for whether people were simply substituting guns for other violent methods. But that wasn't the case.

One thing wasn't quite so black and white though. Because homicides of all kinds (not just shootings) have been on the decline since 1996, the team can’t statistically say for sure that gun laws were the catalyst that caused gun-related murders to drop.

In other words, they were able to show that the 1996 gun laws lead to fewer people being killed by guns overall. They also definitely caused gun-related suicides to drop - but we can't say with statistical significance that they kicked off the accelerated decline in gun-related murders.

But taken together, the results paint a clear picture, the researchers conclude in the Journal of the American Medical Association.

"To me there are two key findings from this study," said one of the researchers, Mike Jones, from Macquarie University in Sydney. "One is that in the 20 years after the passage of gun control laws there has not been a mass shooting in Australia despite an average of two every three years for some time before that. The other is that the acceleration of the decline in gun-related deaths means lives saved."

"We can argue over how many, but the data says lives have been saved," he added.

Similarly, a review of gun control laws in more than 10 countries over the past 60 years, published back in March, showed compelling evidence that the tighter legislation reduced firearm deaths.