Newshub can reveal 50,000 guns have been registered since the Firearms Registry went live in June.
Labour said over time, it will help police track stolen firearms seized from criminals.
But a gun owner Newshub spoke to worries his data in the wrong hands could lead criminals to his home.
Patrick does everything a legal gun owner should do, like keeping them under lock and key - but the recently introduced Firearms Registry is making him feel like the target.
"If that's leaked, that follows you," he said.
"All it's really doing is basically creating a shopping list."
Police have blundered with gun owners' data several times in the past few years. Most recently in July, the new Firearms Safety Authority accidentally copied 147 gun owners into an email.
Two years ago, the police's IT systems were reviwed and some deficiencies were discovered. Areas were found to not meet best practices, and the management of data was highlighted as a key challenge for the police.
But the Police Minister is confident the Firearms Registry is robust.
"I've been reassured that all those checks and balances are done, in particular making sure staff members are only accessing the database for a specific purpose," Police Minister Ginny Anderson said.
And gun owners will be hoping she's right because 50,000 firearms have been registered since it was introduced in June - it is mandatory.
"[It] shows the strong support from the firearms community," Anderson said.
A Firearms Registry was a recommendation from the Royal Commission following the 2019 Christchurch terror attack.
Despite that, the ACT Party has promised to abolish it.
"We have 93 percent firearms crime out there committed by non-licensed holders - these are people who are never going to register firearms," ACT MP Nicole Mckee said.
But with National committed to keeping the gun register, ACT is now open to finding a middle ground.
"If that means negotiating on certain aspects of the registry, then we will look to do that," McKee said. "But our first port of call is to be rid of it to make sure our firearm owners - [a] quarter of a million people out there - feel safe."
