Thousands of firearms remain potentially unaccounted for despite a police campaign for lifetime gun licence owners to renew or hand weapons in.
Police national manager operations Tony McLeod said nearly 50,000 people had not responded by the end of a campaign targeting lifetime gun licence holders to renew or surrender their weapons in 2002.
The Government scrapped the lifetime licences in 1992 for 10-year licences after David Gray killed 13 people in Aramoana in 1990.
Mr McLeod, who said there were about 225,000 licensed firearm owners with about 1.2 million guns in New Zealand, could not confirm how many weapons had since been retrieved.
He said police still actively pursued expired lifetime gun licence holders, but there was "also a process of natural attrition in relation to these".
Napier gunman Jan Molenaar was among those whose general firearms and collector's firearms licences expired in November 2002.
Detective Superintendent Rod Drew said Molenaar had at least 18 guns - nine of which were found in the room where he was found dead.
A further nine were found in his garage and police are not ruling out finding more as their search of the house continues. Many of the firearms were military-style semi-automatic weapons. Police also found a sawn-off shotgun, .308, .223 and .22 calibre rifles.
A police whiteboard used in the operation estimated that Molenaar had 1000 to 10,000 rounds of ammunition.
It also said he had a stick of gelignite and accelerants.
Gun-safety control advocate Philip Alpers said revelations of Molenaar's arsenal were damning for police.
"It's a perfect illustration of how the police have lost control over the situation," he said.
"The police really have no idea of how many guns are out there."
Mr Alpers said the key recommendation in Sir Thomas Thorp's year-long $1 million review of firearms control in New Zealand in 1997 was that all firearms should be registered.
"No 2 was that there should be a buy-back of military style semi-automatic weapons and No 3 was that everybody should be relicensed every three years instead of 10," he said. "Not a single one of the recommendations have been enacted in legislation."
Asked if there would be a ministerial inquiry into lapsed licences, Police Minister Judith Collins said she did not want to prejudice the pending police and coroner's investigations with "premature comment or speculation".By James Ihaka Email James, Patrick Gower Email Patrick
* Fact v Fiction
Details released by the police yesterday make it clear that the Weekend Herald's front-page report on Saturday was right.
Despite widespread claims in other media on Saturday morning that we were wrong and Jan Molenaar was still alive, it is clear that he died on Friday afternoon.
His last communications with his partner and brother were just after 1pm, and a single gunshot was heard at 1.28pm.
From that time there was no further sign of life from the house through phone contact or shooting. As the Herald correctly reported, the police believed him to be dead.