More than 14,000 guns have already been collected in NSW during a nationwide amnesty, with another month remaining before the window closes.
Nine powerful military-grade assault rifles are among more than 14,000 guns collected in NSW during the first two months of a national amnesty period.
NSW Police has seized or been handed 14,466 guns so far, and on Thursday reminded the public there is only one month left before the window closes.
Acting Assistant Commissioner Dave Donohue says the SKS assault rifles, which come in very large calibres, could have fallen into the wrong hands and caused significant damage.
"That in itself, having those nine firearms off the street, is a great result," he told reporters in Sydney.
"Because it is an amnesty, we don't know the history of those firearms - we're not running searches on those firearms."
More NSW residents are taking up the "very rare" offer of surrendering guns with no questions asked in regional areas.
"It would suggest that the proliferation of firearms is higher in the country areas than in city areas," Mr Donohue said.
About 5800 firearms have been surrendered, 7200 have been handed in for registration, 1300 were collected by dealers and 170 prohibited weapons were seized.
They include self-loading and semi-automatic weapons and 13 silencers.
While police say it's difficult to put a number on just how many firearms remain in the community, they believe there could also be many military souvenirs from WWI, WWII and the Vietnam war.
There are more than 2.89 million legally registered firearms in Australia and about 816,000 firearm licences.
A report on organised crime released by Australian Criminal Intelligence Commission last month estimated there are more than 250,000 long-arm guns and 10,000 handguns in the illicit market.
The last national amnesty was called in 1996 by former prime minister John Howard after the Port Arthur massacre in which 35 people were murdered, and was accompanied by a gun buyback scheme.