Gun owners are appalled a parliamentary select committee is giving them just one day to make oral submissions on the government's fast-tracked gun law changes.

Photo: RNZ / Ana Tovey

The Finance and Expenditure Select Committee has decided to close written submissions on the Arms (Prohibited Firearms, Magazines and Parts) Amendment Bill at 6pm tomorrow, and hold in-person submissions tomorrow.

The committee will request oral submissions from "a representative group".

The timeline shocked Council of Licenced Firearms Owners chairman Paul Clark who said he had expected oral submissions would run for several days.

"It's appalling. I was brought up to respect the parliamentary system," he said.

"On something like this, which is fundamental to New Zealand society, you don't just trample over everybody and then say, 'well we've discussed it'."

Mr Clark said he had hoped to get a fair hearing but the short submission time shook his faith in the democratic process.

"This undermines the whole democratic system that we have in this country, there is no other way to say that. It is destroying democracy."

Mr Clark said he did not know if his organisation would be asked to make a submission in person, but he hoped it would be.

He said the committee would not get a representative view of firearms owners' views of the bill from just one day of submissions from a limited number of people.

"I thought we would get a fair hearing because that's the basis of the system we have," he said.

"The minute you start short-circuiting democracy for political convenience you're sending out a lot of alarm bells."

The committee's chairman, Labour MP Michael Wood, said it had about a week to consider the bill and report it back to Parliament.

"It's a pretty tight turnaround, but it's about striking a balance between progressing with this issue with the urgency that the public requires but also have some consideration."

The government could have pushed the legislation through in urgency but instead had provided for a "pretty quick" committee hearing process. It would hear 15 oral submissions and consider all the written submissions, Mr Wood said.

"I can absolutely commit that everyone who submits to our select committee will have their submission considered and looked at carefully and we will be asking the questions of officials to make sure this legislation is fit for purpose."

"Parliament unanimously voted to have this process, and that is because there is unity across the political system that there is a moral onus on us to take swift action on this issue."

Mr Wood said there had been serious work on firearms law, going back to the Thorpe Report in 1997 through to a major select committee report in 2017, which had allowed proposals to be developed.

"Across the 250,000 or so licenced firearm owners the vast majority will not actually be impacted. The ban specifically deals with military-style assault weapons and that is a much smaller subset."

Earlier, Police Minister Stuart Nash had said it would be up to the committee to decide how it organised the submission process.

"I have no doubt the committee will come up with a way, working with officials, to ensure that they hear the voices that they feel they need to hear to make informed decisions," he said.

The committee began its deliberations with a briefing from the police at 5pm on Tuesday.

Senior police used real firearms to show how guns used to kill 50 people in the Christchurch mosque attacks on 15 March were converted from semi-automatic rifle into a restricted military-style weapons by simply adding a magazine with a much higher bullet-capacity.

Police also demonstrated showed how quickly empty magazines could be swapped with full magazines.

Deputy Police Commissioner Mike Clement told the committee the gunman was able to buy his guns and magazines legally with his category A gun licence, and then bring them together to create an illegal and deadly combination.

Mr Clement said the government's bill would make it a lot harder to convert one type of firearm into another.

He said it would also fix a big problem with the current law that saw gun importers and owners make minor modifications to their firearms to prevent them from being categorised as military, and therefore restricted.

"The current categorisation of an MSSA semi-automatic firearm creates a legal definition that is easily circumvented and is difficult to apply. Some semi-automatic firearms use a range of physical contrivances to change the appearance of their MSSAs so the firearm is no longer covered by the legislative definition."

The select committee is expected to consider possible changes to the bill on Friday and report it back to Parliament on Monday.

The government plans to pass the bill into law and gain royal assent by Thursday next week so that it can come into force exactly four weeks after the Christchurch attacks happened.