The pro and the anti-gun lobbies are uniting in calling for an extension to the gun buyback amnesty.

Photo: RNZ / Tess Brunton

The official buyback and amnesty for banned weapons ends today, but a lack of records of how many guns have been brought into the country has led to uncertainty over how successful the buyback has been.

Police were set to hold 22 collection events in towns and cities from Kaitaia to Invercargill today between 8am and 8pm, with the amnesty ending at midnight.

Police said about 50,000 firearms had been handed in since the buyback started six months ago.

Council of Licensed Firearms Owners spokesperson Nicole McKee said that represents less than a third of the 170,000 semi-automatic weapons estimated to be in circulation in New Zealand.

"The collections themselves, is a failure. We could see that some time ago and it's actually disappointing to have to acknowledge that it still is. We expected 170,000 firearms to be handed in, and there's still going to be well over 100,000 still in circulation."

McKee said the 170,000 estimate was from customs data for imported guns and an estimate of 40,000 firearms already in the country.

The buyback had been rushed and her members needed another six months so that the amnesty had the best possible chance of gathering up the thousands of prohibited weapons still sitting in peoples' gun safes, she said.

"It's imperative that there is an amnesty that coincides with education to the firearms license owners to let them know it's not just about semi autos. We don't want to see our members being prosecuted and sent to jail as the government keeps telling them is going to happen."

Gun Control New Zealand's Hera Cook, said many had tried and failed to get a handle on the number of banned weapons already in New Zealand, and Colfo's estimate was just as unreliable.

Photo: RNZ Insight / Philippa Tolley

"We don't know how many guns were in New Zealand to start with. It doesn't matter how much information we have about how many guns have been on. We are not going to know the answer."

Cook agreed with Colfo on the need to extend the amnesty and pointed to what happened in Australia after the Port Arthur massacre.

"They didn't just have the one buyback. They had amnesties later on down the track and they got something like 20 percent of all firearms in Australia."

Police have previously said the amnesty would "effectively" be permanent, with deputy commissioner Mike Clement saying police would not - in the right circumstances - prosecute people bringing firearms in.

Ashburton gunsmith Hamish Bruce said the buyback period hadn't been long enough to modify all the firearms that could have been saved.

Bruce said it took three months to certify gunsmiths who were able to do the modifications to semi-automatic and pump-action weapons, which lost time, and the process itself was bureaucratic.

"We'd never get them all done in the time we've been given," he told Morning Report.

He said the recent privacy breach in the police buyback registration website earlier this month, after German IT contractor SAP introduced an unauthorised software update, had caused big issues for them.

Personal information about gun owners, such as addresses and dates of birth, was available to 66 firearms dealers through the website, which was then shutdown.

"It hasn't been long enough and it hasn't been well thought out or designed and they haven't given us any extra time for errors that have come about from police, things like the data breach," he said.

"You have to get a number from the computer system to start the modification process and a lot of people don't want to go anywhere near that system, and it's not even running, obviously because of the data breach."

Bruce said the scheme was rushed emotively into existence and had proven "long-winded", involving police having to physically inspect the modified gun before signing it off after several bureaucratic processes had been completed.

'Just do the right thing'

Police Minister Stuart Nash was in no mood to extend the amnesty.

The Colfo estimate on the number of semi automatics in New Zealand was an exaggeration, he said, and the 50,000 that had been handed in represented a good result.

"No one has any idea of how many firearms are out there and people say 'well, we've had to look at data, we've extrapolated that -' it really is pie in the sky sort of stuff.

"I look more at the number of Kiwis to participate in this as opposed to the number of guns out there. And about 15 percent of the firearms owning community [that have taken part] feels about right to me."

Photo: RNZ / Dom Thomas

He had a warning for those considering hanging on to banned weapons.

"You can flip a coin. If it lands on tails, then you probably won't get caught, if it lands on heads and we catch you you'll not only lose your licence and your firearms, you face a good chance of losing your freedom because the penalty for having one of these banned firearms is maximum five years in jail.

"Don't take a chance with this. Just do the right thing and hand them in."

As well as the collection events being held today, gun owners can also hand their weapons in at their local police station.

Police have previously also said further waves of buyback events and amnesties were likely, much like the series of collection events Australian police held after the Port Arthur massacre.