Across the state, the number of people with a firearms licence rose by 10 per cent over this period - with one gun now registered for every nine residents.

Some of the biggest rises in gun ownership were in affluent Sydney areas - postcodes that encompass Neutral Bay, Pyrmont and Sydney's central business district, where the number of firearms has climbed by more than 60 per cent since 2010.

More than 850,000 firearms are now legally registered in NSW.

NSW Police firearms commander Mick Plotecki said anecdotally, the combination of United States popular gun culture and a recruitment drive by gun clubs may be behind the rise.

Newcastle Lake Macquarie Clay Target Club president Jason Jenkins said his club had experienced "a mild increase in membership, but we haven't done a special campaign".

"I wouldn't say it's driven by American culture," Mr Jenkins said.

People could not own firearms for personal protection in this country, he said.

"You have to be a hunter or target shooter," he said.

"People are seeing the challenge of clay target shooting and the enjoyment they get from it.

"It's a social activity that the whole family can participate in together and at the same level."

Mr Jenkins said "extreme responsibility" was needed for firearm ownership.

NSW Greens MP David Shoebridge said gains in community safety won since the Howard government's gun buyback program in 1996 had been lost.

"Many people will be quite rightly shocked to find there are many hundreds if not thousands of guns in their suburb," Mr Shoebridge said.

"There are hundreds of thousands more guns now than following the gun buyback. Many farmers and primary producers have a legitimate reason for owning a firearm, but this doesn't explain the thousands and thousands of licences throughout metropolitan Sydney."