Some New Zealand gun owners are upset they're being compelled to hand over their assault weapons for money. Others believe a government-imposed ban on certain semi-automatics following a March shooting massacre is the best way to combat gun violence.

And The Associated Press has found at least one man may have tried to swindle hundreds of thousands of dollars from the system set up to compensate gun owners.

New Zealand is six weeks into an ambitious programme to buy tens of thousands of guns from owners across the country. After the attack at two Christchurch mosques nearly six months ago, the government rushed through new laws banning military-style semi-automatics in a move that's being closely followed around the world.

Prime Minister Jacinda Ardern told the AP in July that most New Zealanders disagree with the US model under which gun ownership is seen as a constitutional right. The new laws in New Zealand emphasise that gun ownership is instead considered a privilege.

So far, owners have turned in more than 15,000 newly banned guns as well as 64,000 parts and accessories. In return, the government has handed them $32 million. But nobody has a clear target for the programme because authorities haven't kept track of the number of guns in the country.

Tentative estimates put the total number of guns in New Zealand at about 1.5 million and the number of weapons that are now banned at up to 175,000. If those numbers are correct, it would mean less than 10 per cent of the banned weapons have been handed in so far. Owners have until December 20 to turn them over or potentially face charges.

Some politicians and opponents say the buyback scheme is a fiasco that is unfairly targeting law-abiding gun owners rather than criminals or gangs. However, Police Deputy Commissioner Mike Clement, a 40-year veteran tapped to oversee the scheme, says it has been working well. He's been traveling the country to some of the dozens of buyback events, and says nobody really knows how many banned guns are out there so any estimates are unhelpful.

"We're just going to keep pushing ourselves," Clement said.

On Saturday, Clement stood in the sun outside an event center near Wellington owned by a dog owners' club. On this day, the centre had been turned into a makeshift venue to hand in guns. Heavily armed officers patrolled while others greeted gun owners cheerfully as they arrived and ushered them inside.

Under the buyback scheme, gun owners get between 25 per cent and 95 per cent of the pre-tax price of a new gun, depending on the condition of their guns. Police take bank details from owners and usually deposit money into their accounts within a few days.

After collecting the weapons, police use a hydraulic machine to crush the barrels and triggers out of shape before tossing them into crates that are loaded onto a truck for disposal.

One of the owners who showed up on Saturday was Paul Campbell, a chiropractor who has enjoyed target shooting since he was 10 years old. Campbell said he was turning in an AR-15 rifle, an AR-10 rifle and a 1961 ex-army SLR rifle that he considered sacred because it was part of a collection used by soldiers in battle. He said he disagreed with the ban and felt it was a knee-jerk reaction to an isolated event. He said previous laws were adequate if they'd been properly enforced.

"Nothing is going to stop crazy behaviour when crazy shows up, except good watchfulness by society to see the cracks, to see the problems, to see problem people," Campbell said.

"This is a mental aberration, it's not a behaviour brought on by the object."

Michael Dowling, chairman of the Council of Licensed Firearm Owners, said gun owners had mixed reactions to the ban and some felt badly treated but most were trying to comply with the law. He said the council doesn't agree with the ban and believes it could create a much bigger black market.

"We're concerned at a high level that the way this has been approached, it potentially could mean a lot of firearms don't get handed in," Dowling said. "And that will create issues for generations to come."

But gun owner Phillip Fee, who was handing in his Remington semi-automatic rifle, said he supported the ban wholeheartedly, especially after the Christchurch shootings. He said there were lots of people who wanted to become infamous or highlight a cause, and that powerful semi-automatics gave them the means.

"There are not too many things that you can take that number of lives with in such a short period of time," he said. "So there has to be some form of control."

As well as some 250 buyback events like the one near Wellington planned over three months, police are also reaching out to dealers to try and collect weapons through them.

Police also have so far travelled to the homes of more than 50 gun owners who have large numbers of weapons to pick up the guns directly.

In all, the New Zealand government has set aside more than $200 million for the buyback scheme. And it seems at least one man may have tried to take advantage. Police are investigating whether the man, who isn't a New Zealand citizen, imported cheap gun magazines from Australia to try to cash in.

Clement said the man showed up at an Auckland buyback event with thousands of magazines seeking to collect hundreds of thousands of dollars in government compensation. A possible flaw in his plan? Clement himself happened to be at the event.

"It's one of those things that didn't look right, didn't feel right," Clement said.

He said police were keeping hold of the magazines and hadn't paid the man any money while they carried out their investigation.

"The vast majority of people are doing the right thing," Clement said. "But there are a handful of people who just, for whatever reason, feel like there might be an opportunity they might be able to exploit."

Brenton Tarrant, a 28-year-old Australian white supremacist, has pleaded not guilty to terrorism, murder and attempted murder charges following the March 15 mosque attacks. He remains in jail ahead of his trial, which has been scheduled for next May.