Gel blasters have been declared a regulated imitation firearm in South Australia, forcing owners to obtain a firearms licence within six months.

They use compressed air to fire a projectile and often look like a real gun.

The importation and possession of gel blasters in the NT remains an offence.

Gel blasters are defined as a firearm in NSW and cannot be possessed with the relevant licensing or permits.

Gel blasters are currently banned in Victoria, you cannot own and buy it without firearm licence.

Changes have been made in Queensland this year to restrict ownership of them.

They might be illegal, but these replica firearms are easily accessible to anyone searching to buy them online, available as "toys" in Australia for as little $150.

The new regulation in South Australia will ultimately result in more real guns in the community, the Shooters Union says.

SA president Peter Heggie says the union opposes the move by police to force people who own gel blasters to obtain a firearms licence.

But he says his group is looking at the positive in the changed situation, with more people likely to get firearms and take up shooting as a result.

It believes if people go to the trouble and cost of obtaining a firearms licence, they are more likely to also buy real guns and potentially try sports shooting or go hunting.

"Welcoming all these new people to the wonderful world of responsible gun ownership is going to do wonders for normalising shooting and hunting in South Australia, and mean there are lots more licensed shooters and actual guns in the state," Mr Heggie said.

SA Police estimate there are currently about 62,000 of the blasters in circulation in SA.

Firearms branch Superintendent Stephen Howard said the firing mechanism met the threshold to be defined a firearm.

In the NT after the seizure of a gel blaster in a Katherine drug raid, Detective Sen.-Sgt Lee Morgan said gel blasters are often designed to have the appearance of a real firearm.

"They have real potential to cause alarm, particularly when people possess them in a public place," he said.

"If police were confronted with an uncooperative person in possession of a gel blaster in a hostile situation, the consequences could be catastrophic," he said late last year.

- with AAP.

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