It is expected to cost the Government between $100 million and $200 million.
The Council of Licenced Firearms Owners (COLFO) said it will seek a longer consultation period following today's announcement.
"We are concerned that around 15 per cent of the Licensed Firearm Owners do not have an online presence, they run the risk of not getting the message in time to prevent them becoming criminals," it said in a statement.
"In the short term, we will seek feedback from all licensed firearm owners so we represent their views. More information will follow with how this will occur.
"We will ask for more detail on what 'a Fair and Reasonable buyback programme' will look like, we thank Cabinet for considering the impact on licensed firearm owners."
Legislation giving effect to the ban will be rushed through Parliament under urgency – Ardern expected the new law to be in place by April 11.
Ardern said the new rules would make New Zealand a safer place, and added that the announcement was just the first step of the Government's response to the terror attacks in Christchurch.
"We will continue to develop stronger and more effective licensing rules, storage requirements and penalties for not complying with gun regulations."
On Monday, Cabinet will consider measures to tighten firearms licensing and penalties, impose greater controls over a range of ammunition, as well as addressing a number of other issues relevant to special interest groups such as international sports shooters and professional pest controllers.
The total number of firearms in New Zealand is estimated to be 1.2-1.5 million.
The Government is also taking action to prevent the stockpiling of weapons.
At 3pm today, an Order in Council – signed by the Governor General – establishes changes to classifications in the Arms Act to mean some firearms have been reclassified as military-style semi-automatic firearms (MSSAs) and are illegal.
These are semi-automatic firearms and shotguns capable of being used in combination with a detachable magazine and capable of holding more than five cartridges.
The effect of this is that it will prevent the sale of MSSAs and assault rifles to people with A-category gun licences.
The Order in Council is a transitional measure until the wider ban takes effect, after the legislation has passed.
In a statement, Police Commissioner Mike Bush said: "As a result of these changes many people who, up until now have owned these firearms legally, will no longer be able to possess them on their current licence conditions,"
There is now an amnesty in place allowing people who have these weapons to hand them over to police.
In the meantime, the weapons have been re-categorised as requiring an E-endorsement on a firearms licence, preventing their sale to people with A-category licences.
The political reaction to the Government's moves has been swift.
The National Party supported the changes and would work with the Government on them, leader Simon Bridges said.
"We don't want military-style semi-automatic weapons and we totally agree that we should limit other high-powered semi-automatic weapons," Bridges told media in Auckland.
"It is imperative in the national interest that we keep New Zealanders safe and secure given the risks to us from here and also internationally."
He said he understood the need for urgency but questioned whether a week-long select committee process was long enough.
"It's also imperative that we get the details right and I look forward to seeing the law, and considering whether a week's select committee is long enough."
Bridges said now was a time for unity and to "get in behind the Government".
"We are backing this".
Bridges said he would be seeking advice from former Australian prime minister John Howard on the buyback scheme proposed by the Government.
Under his leadership, Australia banned semi-automatic weapons and implemented a buyback scheme following the Port Arthur massacre in 1996.
Around 700,000 weapons were handed back during that amnesty.
Deputy Prime Minister Winston Peters, also the leader of New Zealand First, said the ban was a "necessary and significant policy response".
"On the afternoon of the 15th March, our country changed forever. As a Coalition Government, we have worked constructively to change gun laws."
He said there was no reason for access to military-style semi-automatic firearms and this action is to ensure what happened in Christchurch never happens again.
Peters pointed out that exemptions for legitimate business use have been made to acknowledge that some guns have legitimate purposes in farming communities."
"This a critical step by the Government with further work to done."
The Green Party welcomed the proposed ban.
"Banning military-style semi-automatic weapons and assault rifles makes everyone safer. Banning these guns is the first step towards systemic changes to our gun laws," co-leader James Shaw said.
"We are working constructively with our Government partners on further much-needed action to tighten access to guns in our country.
"I am pleased that our Government is acting so swiftly and decisively to rid the country of firearms designed to kill people," Shaw said.
But Act Party David Seymour criticised the "rushed process" of the legislation and said it would "deny the public the chance to have their say".
He said it could lead to legislation that failed to solve the problem.
"Trying to pass a law in less than three weeks in a recipe for bad lawmaking."
Ardern did not think this would be the case.
She said that the "vast majority" of Kiwis would support a ban on semi-automatics.
Questions and Answers
1. What semi-automatic firearms will be affected by the ban?
The ban will apply to all firearms are now defined as Military Style Semi-Automatics (MSSAs) and will also include assault rifles.
2. What semi-automatic firearms will NOT be affected by the ban?
There is a balance to be struck between public safety and legitimate use. The changes exclude two general classes of firearms which are commonly used for hunting, pest control, stock management on farms, and duck shooting:
• Semi-automatic .22 calibre rimfire firearms with a magazine which holds no more than 10 rounds
• Semi-automatic and pump action shotguns with a non-detachable tubular magazine which holds no more than five rounds
3. What semi-automatic firearms are affected by today's Order in Council?
Two types of firearms are now defined as Military Style Semi-Automatics (MSSAs):
• A semi-automatic firearm capable of being used with a detachable magazine which holds more than five cartridges
• A semi-automatic shotgun capable of being used with a detachable magazine which holds more than five cartridges
4. I have an A-Category firearms licence and now own MSSAs. What should I do?
It would normally be an offence for an A-Category licence holder to possess an MSSA, punishable by up to three years in prison or a $4000 fine. However, a transitional period gives time for people to comply with the law, if they take certain steps. The transitional period will be confirmed next month. Firearms owners who unlawfully possess an MSSA now have three options:
• Voluntarily surrender the firearm to Police for safe disposal.
• Complete an online form on the Police website to arrange for the MSSA to be collected, while details are finalised for compensation under a buy back scheme
• Sell or gift the firearm to a person who has an E-Category licence and a 'permit to procure' the weapon
5. Are Police geared up to receive large numbers of MSSAs?
Yes. They will work with the New Zealand Defence Force to enable safe storage, transport and destruction of MSSAs. Police are establishing an online form which will make it easier for firearms owners to arrange for Police to collect the MSSAs. The online form will go live over the weekend. It will not be practicable for firearms owners to physically return their weapons to Police stations without prior approval. Where extra administrative staff are required they will be hired on fixed-term contracts.
6. Will this lead to stockpiling of semi-automatics?
No. The changes under the Order in Council take effect immediately. Anyone who now unlawfully has an MSSA, which yesterday was a lawful firearm, needs to take steps to comply with the law.
7. Will some firearms dealers be breaking the law if they have these MSSAs in stock?
Some firearms dealers only hold A-category licences. In order to comply with the law, they could sell their stock of semi-automatics to a Category-E licence holder or return them to their supplier.
8. What are the statistics for firearms licences and firearms in circulation?
• There are 245,000 firearms licences
• Of these, 7500 are E-Category licences; and 485 are dealer licences
• There are 13,500 firearms which require the owner to have an E-Cat licence, this is effectively the known number of MSSAs before today's changes
• The total number of firearms in New Zealand is estimated to be 1.2-1.5 million
9. What further issues are being considered?
Cabinet will consider further steps on March 25. These will include measures to:
• Tighten firearms licensing and penalties
• Impose greater controls over a range of ammunition
• Address a number of other issues relevant to special interest groups such as international sports shooters and professional pest controllers, such as DoC.
• Future-proof the Arms Act to ensure it is able to respond to developments in technology and society
10. How will the buyback work, and who will administer it?
Police, the Treasury and other agencies are working through the detail. More information will be available when the legislation is introduced next month. The compensation will be fair and reasonable based on firearm type, average prices and the age of firearms.
11. What is the cost of the buyback likely to be?
That is very difficult to judge, given the limited information about the total number of firearms affected by this change. Preliminary advice suggests it could be in the range of $100m-$200m. The buyback will ensure these weapons are taken out of circulation and that we fulfil our obligations under the law.
