Key Points:

A gun collector who sold restricted firearms on the black market has placed the community at "grave risk" and created the potential for "long-term tragic consequences", a judge says.

Coromandel collector John Noel Mabey was yesterday sentenced to 21 months in prison after pleading guilty to a charge of selling pistols, military-style semi-automatic firearms, and restricted weapons to unlicensed people.

The 30 guns Mabey admitted selling included Browning and Glock pistols, and four machineguns capable of firing up to 250 rounds.

The firearms are estimated to have fetched a total of $180,000 to $200,000, after a Colt 45 pistol from his collection was offered to an undercover police officer for $7000.

Mabey, a 44-year-old sickness beneficiary, had sought home detention but Judge Phillip Connell said his offending warranted time behind bars for one over-riding reason:

"The fact that the community here is now in a position of grave risk through these firearms being used for illicit purposes."

Judge Connell said most of Mabey's guns had fallen into "the wrong hands", including one used by a fugitive to shoot at police, and others found in raids on gang premises in the Waikato and Auckland.

Police records showed Mabey had 121 restricted firearms before police went to do an inspection at his Hot Water Beach property in July last year.

Mabey was not home, and six days later, his guns were reported stolen after his mother and daughter arrived at the property to find a window open and Mabey's gun safe empty.

Police allege the theft was staged, but Mabey has denied a further charge of making a false burglary complaint.

However, Judge Connell said evidence against the 44-year-old on that count was strong, including forensic tests which showed the window and gun safe locks had been tampered with while open.

Of Mabey's 121 missing guns, only 10 have been recovered, including one used in a non-suspicious fatal shooting which police said involved consumption of recreational drugs.

At the Hamilton District Court yesterday, prosecutor Ross Douch said Mabey had "failed appallingly" in his duty as a firearms licence holder and it would take years to recover the guns he had admitted illegally selling.

"The harm they can do in the interim is incalculable. Every bank teller, every dairy owner who has a firearm pointed at them is being indirectly traumatised by the actions of people such as this prisoner."

Mr Douch said Mabey's motivation was money, after he took out a loan for $576,000 and was unable to repay almost $70,000 in interest six months later.

"He needed cash. He had a firearms collection and he also had criminal associates."

According to a summary of facts agreed upon by Mabey's lawyer, Mabey formed a relationship with a drug dealer called Evans in late 2004 or early 2005 who had many contacts in the criminal fraternity.

The summary said Evans would locate prospective buyers for Mabey's firearms, and receive a cut from each sale.

Evans told police he facilitated the sale of 30 to 40 handguns belonging to Mabey with prices ranging from $4000 to $10,000. Mabey had also made Evans aware he was making other sales, the summary said.

Judge Connell said Mabey's guns had the potential to cause death or injury, and he must have been aware when he sold them that they would likely be used for criminal purposes.

"[The case] involves offending that may well have long-term tragic consequences...That's what you've unleashed on the public."

Mabey's lawyer, Peter Kaye, asked the judge to take into account Mabey's previously clean record, but Judge Connell dismissed as "just short of ludicrous" Mabey's explanation that he had got into trouble after not keeping the proper paperwork when he sold a pistol.

Under the Arms Act, Mabey faced a maximum of three years in prison, which the judge said was low considering the danger to the community of such offending.

Detective Senior Sergeant Greg Nicholls, the officer in charge of the case, said Mabey's actions were abhorrent and his missing guns would continue to pose a threat.

"The potential risk to the public and to police will go on for years until we recover all of these firearms."