Act Leader David Seymour says he is "mournfully proud" to have been proved right over the failure of the Government's gun buyback scheme.
Today is the last day of the amnesty, which was launched after the Government banned military-style semi and automatic guns after the March 15 terror attack.
Police Minister Stuart Nash said there have been more than 56,000 now-prohibited guns taken out of circulation.
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He said that from tomorrow, those in breach of the law face risk of prosecution and up to five years' jail, as well as the loss of their licence.
But not everyone is as optimistic as Nash when it comes to the success of the scheme.
"It's difficult to imagine that, not only the Government, but all of Parliament could have screwed up worse than the knee-jerk legislation that they forced through in April,"
Seymour said today.
"The Act Party takes no comfort from being vindicated from the failure of the gun buy-back."
He said it's something he's "mournfully proud" of.
His comments come as the Council of Licensed Firearms Owners (COLFO) estimate that roughly two thirds, around 100,000, now-banned firearms remain in circulation.
The lobby group released the results of a survey – taken from 5000 of its members – that showed the ban had led to a sharp decline in gun owners' trust in the police.
COLFO spokesperson Nicole McKee said the "high-handed attitude of the Police hierarchy has led to the almost complete failure by Police at a frontline level to convince firearm owners to hand in their firearms".
She said many owners of the now-prohibited firearms would hide them to make sure the police cannot get their hands on them.
This was "despite our best efforts to encourage compliance".
However, in an August, COLFO issued a press release which suggested they were not, in fact, encouraging compliance.
"The Council of Licenced Firearm Owners (COLFO) has today suggested that members hold on to banned firearms until the Government announces better channels and compensation before the December 20 2019 amnesty deadline."
When challenged on this today, McKee told media that the reason for the press release was to put pressure on the Government to provide other buy-back alternatives because there was "so much mistrust" of the police.
She said that these alternatives actually helped bring in more now-unlawful firearms to Police.
Like Seymour, National's justice spokesman Mark Mitchell has also branded the buy-back a failure.
"As of today, Police estimate they have received over 50,000 firearms, but this is less than a third of what Police advised could be out there.
"The result is a lot of confusion and lack of engagement. The buy-back has arguably been one of the Government's most important policies. This is yet another failure to deliver."