People with recently outlawed firearms have until December 20 to hand them in or face five years in jail after Police Minister Stuart Nash ruled out extending the amnesty.
The announcement is being described as unfair by the gun community because certain options for handing in guns - such as to dealerships - have only just been made available.
Nash made the announcement while speaking at the Police Association's annual conference in Wellington this morning.
"I can state absolutely for the record, there will be no extension or no exceptions."
A six-month amnesty and buy-back scheme was put in place after gun law reforms - supported by all parties but Act - banned most military-style semi-automatic (MSSA) firearms in the aftermath of the March 15 terrorist attack.
Nash told the conference he had heard stories about some people who have not handed in their guns because "misguided people" were telling them not to do so.
"There are false stories out there which are suggesting that he is going to change his mind or extend the buyback or change the pricing.
"Well, I can tell you that I am not going to extend the buyback or change the pricing or change my mind.
"If people haven't handed in their banned firearms by the 20th of December, they will get no money and they will face up to five years in jail if we find them."
Council of Licenced Firearms Owners (COLFO) spokeswoman Nicole McKee said Nash risked angering the gun community even more by ruling out any extension.
The option of handing in banned firearms to dealerships had only just been opened.
"They've also only just made available the gunsmiths who can modify firearms and details on how a person can apply to have an unusual firearm looked at for compensation.
"Yet people are being told to comply by December 20 or face imprisonment. That's unfair and unreasonable."
The number of prohibited firearms is unknown, but estimates range from as low as 56,000 to 250,000.
There are about 14,000 that have been registered under E-Cat firearms licences.
At last count, Nash said there have been about 30,000 prohibited weapons have been handed over to police, and $56 million had been paid out.
"That's 30,000 weapons designed to kill people – not dear or goats or possums or rabbits."
He added that more than 100,000 prohibited parts, such as high-capacity magazines have been handed to police.
Last month Police Deputy Commissioner Mike Clement said police would use discretion if they found people with illegal firearms after the amnesty expired on December 20, but they should not expect a police warning.
"Why would you take that risk? Please don't be the person that looks back on the 21st of December and says, 'Gee, I missed that opportunity and now I'm unlawfully in possession of a firearm.'
"Bring your guns in."
Meanwhile the COLFO has written to Nash, saying it intends to seek a judicial review if its questions over the ban on gun ammunition are not addressed.
A spokesperson for Nash said he had received a letter from COLFO and a response will be forthcoming.