The gun lobby is demanding the Government dramatically up the amount it's offering to owners of firearms banned in the wake of the Christchurch attacks.
Police Minister Stuart Nash and Finance Minister Grant Robertson on Thursday revealed the total compensation package had been boosted to $200 million, thanks to a cash injection from ACC.
But Nicole McKee of the Council of Licensed Firearms Owners says more than $1 billion will be needed to stop gun owners "having a bit of a whinge".
"What we're looking at is not the full value of the firearms that have been confiscated by this Government," she told The AM Show on Friday.
"They did promise that they would be fair with this. They've taken a whole stack of law-abiding citizens - 250,000 of them - promise them that they would look after them, and in actual fact they have no intention of doing that."
While there are almost 248,000 licenced firearms holders in New Zealand, only a fraction are likely to own weapons banned by the Arms (Prohibited Firearms, Magazines, and Parts) Amendment Bill.
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With no legal requirement to register firearms, the total number is unknown. Robertson and Nash said on Thursday police know of approximately 14,300 military-style semi-automatics (MSSA) currently in circulation which are now illegal. It's been reported only 7000 New Zealanders hold an E endorsement which allows them to have such weapons.
The Government's allocated budget sets aside about $14,000 per MSSA. In March, McKee said there could be as many as 400,000 weapons in New Zealand covered by the new legislation - that would leave about $500 per MSSA.
"There was extremely good consultation with gun owners, gun dealers, the likes of farmers who are going to be affected by this gun buyback," Labour MP Kris Faafoi told The AM Show.
"It's taxpayer money... we have to be responsible with that too."
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McKee said the advice gun owners gave to KPMG, which ran the consultation on behalf of police, has been ignored.
"The advice that KPMG did get from some of the firearms community... was not completely listened to or adhered to when the Government came out with their buyback figures. The people involved in that discussion are saying, these are not the figures that we gave them."
The Council of Licensed Firearms Owners is likely to take the Government to court, even though the buyback gives gun owners the option to challenge the Government's valuation of their weapon if they feel it's inadequate.
"In some instances it's thousands of dollars off. There are a lot of firearms that are not on that list as well, so there's quite a bit of concern there from some of the firearms owners," said McKee.
"If it's worth $10,000 or $15,000 then I think someone who is obviously angry enough to make a point of speaking about it publicly wouldn't mind paying $100 to make sure they can get a fair value for their firearm," Faafoi responded.
National MP Judith Collins said while her party backed the legislation, it was on the understanding the buyback scheme would be "very generous".
"If you're not more than generous, you'll end up with people who are absolutely riled up," she told The AM Show. "Some of these firearms are worth tens of thousands of dollars."
She said Australia's initial gun buyback scheme started off offering $300 per weapon, "but the Howard government found they just had to go out there and pay market price".
Australia's gun buyback held in the wake of the Port Arthur massacre cost AU$304 million in compensation, and recovered almost 650,000 firearms - about AU$470 per weapon, almost exactly what's on offer in New Zealand if McKee's upper estimate of 400,000 prohibited weapons is accurate.
While suggesting the Government's offer isn't generous enough, Collins said at the end of the day no one needs an assault rifle with a large capacity.
"If you can't shoot an animal and put it down with five shots, there's something seriously wrong with [you]."