Gun control advocates want the government to restrict or block the import and ownership of a type of rifle that is easily cut down to serve as a handgun.
Police say at least 163 of the 782 Alfa carbines and Alfa hunters brought into the country from 2019-2021 have been passed on to criminals.
Campaigners want tighter restrictions on specific rifle
Handguns have not been a big feature of gun crime in New Zealand, representing just seven percent of the firearms police seize. However, they say the Alfa weapons pose a risk.
The guns look like a revolver handgun with a rifle barrel and stock and once cut down are indistinguishable from a purpose-built handgun.
One officer has described Alfa weapons as coming "with everything except the hacksaw".
The guns brought into New Zealand had a variety of calibres ranging from .22 to the larger .45 calibre and 9mm.
Police successfully blocked an application to import more of the rifles in 2022.
However, there is no blanket ban on the weapons - each import application is considered on its merits.
One of the founders of Gun Control NZ, Nik Green, said the Alfa weapons allowed criminals to evade the tight rules that limited their access to handguns.
"It's pretty worrying because of course handguns can be easily concealed and moved around," he said.
"The reason that handguns don't feature very much in crime is that they're very, very tightly regulated. They're all registered. People who want to have them have to go through a higher and stricter regime and they have to maintain an active participation in clubs.
"You don't have that same control with these Alfa carbines which means there's much more risk of them getting out into the wrong hands."
Green said tighter restrictions were appropriate.
"Where you have firearms that represent a high risk to the public, be it pistols, semi-automatics, these ones which can be easily modified to be concealed, you need tighter controls and ideally a prohibition or much tighter restrictions," Green said.
"The police have to play a cat and mouse game with keeping an eye on all these import controls and it wastes their time and effort and they've got better things to do when it comes to public safety."
Long-time firearms safety campaigner Graeme Easte said the guns posed a particular risk because they could be easily cut down and concealed.
He said the weapons could get around rules designed to limit the sale and ownership of handguns and they should be banned altogether.
"There should be a blanket ban," he said.
"The minister keeps talking about giving the police more powers. This is one power that the do need, to prevent these sorts of weapons coming into the country or getting into general use."
Hugh Devereux-Mack from the Council of Licensed Firearms Owners said there was no need for further restrictions.
"These are A-category firearms that are approved for sale in New Zealand by police. The fact that criminals have seen them as an easy one to cut down and modify illegally for criminal use can be applied to many different including shotguns and Ruger 10/22s," he said.
"I don't think we should be restricting the use of what is available legally to people who obey the law based on the actions of criminals who will break the law regardless."
Detective Senior Sergeant Mike Beal, formerly of the police firearms investigation team, told RNZ that handguns had always been desirable among criminals because they were easily concealed and could be operated with one hand.
However, handguns were not common in the criminal world and offenders tended to use cut-down rifles and shotguns instead.
"These firearms do pose a risk. The number of them that are turning up in the possession of gang members or criminals or unlicensed persons just demonstrates that."
Beal said police had investigated cases in which individuals bought multiple Alfa carbines or Alfa hunters and sold them on to criminals before a firearms register was introduced.
"Those people who have been involved in diversion, who have been investigated successfully and prosecuted, almost without exception their first response to to our team when they were spoken to was: 'I sold it to another firearms licence holder, can't remember his name, can't remember where I met him, yeah, I've got no details, but yeah I definitely saw his licence'. And that explanation actually fulfilled the requirements of the Act at that time," he said.
Police had completed investigations into the whereabouts of 64 of the guns and recovered eight - all of which had been cut down, Beal said.
The investigations involved 21 individuals, including 15 firearms licence holders, involved in diverting the guns to criminals.
Meanwhile, Associate Justice Minister Nicole McKee said the government was committed to comprehensively rewriting the Arms Act.
She said the public could have their say on any changes during the consultation process.