More than 56,000 banned firearms have been handed in under the Government's buyback scheme, and Opposition MPs have criticised it as a failure.

The official amnesty period for prosecution of owning banned firearms ends at midnight tonight, and there have been a number of events being held around the country for any last minute rush.

ACT leader David Seymour did not beat around the bush saying how he felt about the buyback.

"It's difficult to imagine how not only the government but all of Parliament could have screwed up worse than the knee-jerk legislation that they forced through in April.

"The ACT Party takes no comfort from being vindicated by the failure of the gun buyback," he said.

Seymour said it had caused law-abiding owners to engage in civil disobedience because Parliament eroded the respect for the law.

National's Mark Mitchell said the six months would have been enough if the Government had better consulted with owners.

"I think they need to go right back start talking and listening and engaging and I think when you look at the numbers that have come in then they should review whether they should put an extension in place," he said.

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Council of Licensed Gun Owners (COLFO) spokesperson Nicole McKee said they estimated there were still about 100,000 illegal firearms that had not been collected.

"From tomorrow there will be a number of good people who will be made criminals from this Government's arrogance and this is the new normal," she said.

COLFO has united with anti-gun lobbyists in calling for an extension to the amnesty on prosecution of people with illegal firearms.

Police Minister Stuart Nash was against the idea, and said more than 56,000 guns had been handed in, rejecting any talk of the buyback scheme being a failure.

"I simply don't buy into that, KPMG from the outset gave us an estimate of between 56,000 guns and upwards so we are within the estimate they gave us.

Remember we have always been clear we simply have no idea how many guns are out there, it's the reason there needs to be a register, but I think this has been a huge success," he said.

Police have previously said the amnesty would "effectively" be permanent, with deputy commissioner Mike Clement saying police would not - in the right circumstances - prosecute people bringing firearms in.

Those calling for an extension to the official amnesty have noted that Australia's programme, which New Zealand's was partly modelled off, had repeat buyback events and amnesties further down the track after the initial one.