Carolyn Loughton still carries a bullet in her shoulder from one of the world's worst mass shootings that killed her daughter 20 years ago and galvanized Australia to drastically clamp down on guns.

Loughton threw her body over her 15-year-old daughter Sarah, but could not save her from a gunman with two semi-automatic assault rifles who methodically took headshots in a Port Arthur, Tasmania, cafe on April 28, 1996, killing 35 people.

In response, the Australian government severely restricted ownership of semi-automatic firearms, pump-action shotguns and other rapid-fire weapons. It also bought back nearly 700,000 guns from the public at a cost of $390 million.

Since then, the country has experienced only one case that meets the generally accepted definition of a mass shooting - four deaths in a single event - a 2014 incident in which a farmer shot his wife and three children before killing himself. Now a person living in America is around 10 times more likely to be killed by a gun than in Australia, and President Barack Obama has held up Australia's strict gun laws as a good example after repeated mass shootings in the US.

Ceremony planned

Today, as Australia approaches the 20th anniversary of the Port Arthur tragedy - to be remembered with a ceremony on Thursday - there is renewed debate over guns amid a review of the landmark National Firearms Agreement, adopted after the 1996 attack, and the loosening of some gun-related regulations.

The review was recommended after a government inquiry into the December 2014 Sydney cafe siege that left two people and the gunman dead.

Gun enthusiasts fear that any changes to the agreement could mean greater restrictions on gun ownership, while gun control advocates say the country is backsliding on its restrictions.

Taking center stage in the debate is whether Australia should import the Adler A110 shotgun, a Turkish-manufactured lever-action weapon that can fire eight cartridges in as many seconds. That's almost as fast as a pump-action shotgun.

Illegal guns the problem

Loughton, now 60, sees the Adler question as a tipping point. She is speaking out for the first time to protect the country's stringent gun laws.

"I've probably got 20 years of my life left. I wouldn't have thought that I would ever have to go down this track," said Loughton. "But I have seen and I know more than anybody should ever have to experience, and on my last breath on my last day, I don't want to say I could have done something."

Pro-gun activists argue that Australia's real problem is illegal guns. They point out that the Islamic State-inspired gunman in the Sydney cafe siege, Man Haron Monis, never held a gun license and his sawed-off pump-action 12-guage shotgun had not been registered. Authorities could not trace where Monis had obtained it.

Sen. David Leyonhjelm, a vocal gun proponent, complains that Australians have become "disarmed victims."

Loughton and gun control advocates say they see the erosion of gun controls. They point to relaxed requirements to establish the legitimate need for a gun and decisions by several states to waive a 28-day waiting period for a gun owner to apply for a permit to own more than one weapon.