Legislation to ban a range of semi-automatic firearms and implement a buy-back scheme got the backing of all the major political parties during its first reading at parliament today.

Photo: AFP

The Arms Amendment Bill, requiring owners of semi-automatic weapons and military style semi-automatics to hand them in to authorities by the end of September, was debated and passed by MPs in parliament this afternoon.

Just one MP - ACT Party leader David Seymour - voted against the bill.

The buy-back scheme is expected to cost between $100 to $200 million, although Acting Deputy Prime Minister Winston Peters said this morning it could be up to $300m.

The debate began after Mr Seymour failed to block MPs from passing the new legislation quicker than usual because he was late to the House after talking to media about his plans.

Photo: VNP / Phil Smith

Police Minister Stuart Nash said gun-ownership was a privilege not a right.

"The most critical weakness in our firearms law is that too many people have legal access to too many semi-automatic firearms capable of causing significant harm.

"The current arms act has a legal definition for military style semi-automatics ... that is easily circumvented and is difficult in practice to apply."

He said the government was not targeting all gun owners.

"It is important to reiterate the legislation is not directed at law-abiding firearms owners who have legitimate uses for their guns.

"Our actions, instead, are directed at making sure March 15th never happens again."

Mr Nash said he hoped the buy-back scheme will be ready by the the time the bill is passed into law and receives royal assent, which is likely to be in about a fortnight.

Photo: RNZ / Richard Tindiller

National Party police spokesman Chris Bishop said the public wanted action on gun laws, and parliament had heard them.

"Parliament has heard those messages. We will act.

"This Bill strikes an appropriate balance ... between protecting legitimate, law-abiding, licenced firearm owners, our hunters, our shooters and our farming community while also making sure the public don't have access to things like military style semi-automatics weapons and assault rifles."

However, National's Amy Adams wanted more clarity on how the buy-back scheme would work.

"What I'm interested in is how the buy-back scheme would work so that the gun-owners that we are about to deprive of their lawfully held possessions ... how they are going to be compensated, when, under what schedule [and] what they can expect.

"I don't like, as a matter of practice, passing legislation and saying, 'don't worry, we'll compensate you but we'll tell you what the conversation looks like later'.

"I think the public of New Zealand deserve to know a little bit more about how that will work."

Photo: RNZ/Rebekah Parsons-King

National MP Judith Collins said she wanted to see a firearm prohibition order enable police to go into gang houses to seize illegal firearms.

"One of the opportunities for this new legislation is to think about, in the second tranche [of gun law changes], bringing in that firearm prohibition order.

"Best way forward is to give police the powers, give them the fire power to do it and get on and take them because I'm sick and tired of hearing people emoting about how they're feeling sorry, but they're not giving up their firearms."

Photo: RNZ Lynda Chanwai-Earle

Green Party MP Golriz Ghahraman said previous gun laws failed the Muslim community, and fixing the gun laws was an urgent and necessary step.

"This is the beginning of the change needed to making New Zealand a place where we all feel safe and truly at home.

"New Zealanders want this change, they want it now, and with that strong mandate we are making the change today."