One licenced owner caught up in the breach fears he's at risk of a home invasion.

"I've got security cameras, I've got an alarm system, I've got a safe that's bolted to the concrete floor," he told Newshub.

"I take every single measure that I possibly can. And to have my private information leaked like this just puts myself at risk."

He was one of 147 gun owners who were accidentally cc'd in an email sent out by the new Firearms Safety Authority.

Operations Director Richard Wilson has apologised and is promising "a rapid review of its processes around the sending [of] large batches of email".

The anonymous licenced owner said he doesn't trust the police to handle firearms data.

"I absolutely don't trust the police to keep that information secure."

That's because it comes after sensitive documents on gun owners were stolen from a central Auckland police station last year. Back in 2021, 38 firearms licence applicants were copied into the same email, and then in 2019, during the gun buyback, a massive breach exposed details of gun owners' names, addresses and firearms. 

The Firearms Safety Authority sits within the Police. It was established, along with a gun registry, in the wake of the 2019 Christchurch shooting. But opponents argue that registration of firearms doesn't work because illegal guns will never be registered anyway.

"We need to create that trust between New Zealand Police and licensed firearm owners again but it's really hard when police keep making these fundamental, basic mistakes," said ACT's firearms spokesperson Nicole McKee.

But Police Minister Ginny Andersen is optimistic.

"That email sent to people had no address or further information, only an email address. I know it's unacceptable but it has not undermined the integrity of the system of the registry," she said.

But the anonymous gun owner does not share her optimism and is doubling down on his own security to ensure his guns don't get into the hands of criminals.