New Police Firearms Registry data shows an extra 65,000 firearms were registered in NSW in less than two years, bringing the state's total pool of legal guns to 915,000.

But for three months from July 1, registered and unregistered firearms will be able to be surrendered, no questions asked, under the national gun amnesty.

“The aim of this is to get unwanted and unused firearms out of the system,” Mr Coulton said.

“It might be firearms that have been handed down from a deceased estate or people don't need them anymore, and maybe there were some that were left behind in the last round 20 years ago and people feel they may want to rid themselves of those firearms and this is a great opportunity to do that.”

Mr Coulton acknowledged Australia has a problem with illegal firearms, but said the government had no expectation “the criminals are going to hand in their pistols”.

“At the same time this is not targeting law-abiding gun owners,” Mr Coulton said. “It's just that if you have a firearm that's no longer needed, it's an opportunity to hand them in.”

The government estimates there are 260,000 illegal guns in the community across Australia.

But from July 1, gun owners, licensed or unlicensed, will be able to surrender registered or unregistered firearms at licensed firearm dealers.

People will also be able to call their local police station to arrange to hand in their firearms.

Western region commander Geoff McKechnie has welcomed the amnesty.

“[It will] give people an opportunity to surrender firearms if they have come into possession by a means other than by the registration and licensing process,” Commander McKechnie said.

“So it’s a great opportunity for people who have firearms to hand them in to a licensed firearms dealer or police.”

The amnesty will also allow for those gun owners who aren’t licensed, or for people with unregistered firearms, to obtain the necessary documentation to make their gun legal.

“It could be that firearms that have been stolen in the past may be handed in by people that have come into possession of them,” Commander McKechnie said.

“Removing any gun from an unlawful situation has got to be a positive.”