The Police Association is backing the Government's second tranche of gun reforms, which includes tighter controls on firearms licence holders and a national register for all firearms.
But concerns have been raised by Federated Farmers and the Council of Licenced Firearms Owners (Colfo), who say that a national register is impractical, costly, and unlikely to make New Zealand any safer.
Prime Minister Jacinda Ardern announced the reforms today, which are expected to be in place by the start of next year.
They include a national gun register for every firearm and firearms licence holder, warning flags that would be grounds for police to revoke a licence and confiscate guns, requiring a firearms licence to buy ammunition, and a ban on visitors to New Zealand getting a firearms licence.
Ardern said that the new rules would have helped prevent the terrorist attack on March 15, because the alleged gunman would not have been able to buy guns in New Zealand.
Police Association president Chris Cahill said a national register would show officers how many firearms were registered to an address.
"This should help police officers turning up to volatile family harm incidents, which account for a huge percentage of an officer's daily work.
"Not having any idea of how many guns are in circulation in New Zealand, who has them, and whether they are securely stored, adds a real pressure to the work of our members."
Cahill also welcomed the introduction of new firearms offences and the signalling of higher penalties for breaching firearms law, which would punish gang members caught with illegal guns.
"Both these initiatives will address criticisms from some sectors that there is no real penalty for gang members and other individuals who are caught with stolen firearms, or who use guns in the course of crime."
Gun Control NZ welcomed today's announcement, saying the new rules would contribute to a safer New Zealand.
"Registers encourage gun owners to take greater care with their guns, they help police solve gun crimes and enable greater restrictions on access to guns by those who are unfit to hold a licence," co-founder Nik Green said.
But Colfo spokeswoman Nicole McKee said criminals would ignore the register and continue to use guns for illegal ventures, a position supported by Act leader David Seymour, the only MP to vote against the previous round of gun law reforms.
"Criminals, of course, will not register their guns, making the exercise almost worthless. Even if an unfit and improper person has a gun, what difference does it make if it is registered?" Seymour said.
McKee noted how a register in Canada was scrapped after costs reportedly blew out from CAD$2 million to CAD$1 billion, but Police Minister Nash said that was because it started in the 1990s, when technology was much less advanced.
Colfo was cautiously supportive of other parts of the reforms, including requiring a licence to buy ammunition, magazines and gun parts.
McKee also supported stopping visitors from getting a gun licence, saying they should not have the same privileges as New Zealand citizens.
She raised issues of privacy around the police warning flags, which would allow police to revoke a licence and confiscate guns if a licence holder was, for example, promoting extremism.
Nash said that current privacy laws would apply, meaning that information sent to police - including from a GP with concerns about the mental health of a patient - would not be able to be shared and would have to be substantiated before any action was taken.
He said that the cost of firearms licences would likely rise, but that would form part of a discussion document later this year; police spent more than $13 million a year to administer the system, yet received only $4 million in fees.
The Government shunned a recommendation from the 1997 inquiry, led by Sir Thomas Thorp, to put in law that having a firearm for self-defence is not a legitimate purpose.
Instead the new law, expected to have a three-month public consultation process and pass by the end of the year, will say that owning a firearm is a privilege, not a right, and that came with an obligation to demonstrate a high level of safety.