Gel blasters - spring powered, battery operated, plastic guns which fire polymer gel beads - have been rising in popularity as an "environmentally friendly" and "less painful" alternative to paintball guns.

But, in NSW, they're considered prohibited firearms and a number of Central West locals have been hit with criminal charges over their possession.

"I guarantee there are a lot of people who don't realise they're illegal here," said Nicky Bourke, co-owner GunPro in Dubbo, a licensed firearms dealership.

Under the Firearms Act of NSW, gel ball blasters are classified as "air guns", and therefore, Category A firearms - meaning, they are only legal to possess with a "valid permit". However, if the gel ball blaster "substantially duplicates in appearance" a military style firearm, like most on the market, they are prohibited.

Ms Bourke said her store has seen a number of locals surrendering gel blasters under an ongoing national firearms amnesty, which started in July last year, where people can turn in unlicensed or prohibited firearms without fear of penalty.

"We had a few separate mothers come in at the very beginning of the amnesty, and the reason they surrendered them was - within the household - people have got firearm licences. Being caught with a prohibited weapon would jeopardise firearms licences for the rest of the household," she said.

"They're definitely buying them online. If it's someone from within Australia they would have a notification that if you're from NSW you can't buy it. But if it's an eBay seller from overseas, they wouldn't care."

Despite their illegality, gel blasters and their accessories are readily available online and gel blaster "ammunition" - water absorbent polymer beads like those used in vases and potted plants - can also be bought in many craft, hobby and homeware stores.

A simple search on eBay turns up hundreds of listings selling blasters for as little as $20. Most sellers are based overseas where gel blasters are legal, and the marketing is often aimed towards kids with one listing reading "a new and interesting toy" which is "perfect for birthdays".

There are also a number of online gel blaster stores based out of Queensland, the only state or territory in Australia where gel blasters are classified as a toy rather than a firearm or weapon, so they can be owned without a permit or licence.

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NSW Police take possession of gel blasters seriously. The maximum penalty for possessing a gel blaster in NSW is five years imprisonment or a $5,500 fine.

In January last year, a 17-year-old boy was given a caution for the possession of a gel blaster rifle after the firearm was found during a vehicle stop in Mudgee.

More recently, a 54-year-old from Narromine was sentenced to a one year and six month intensive corrections order after he was caught importing gel blasters he bought on eBay and storing them in his caravan. The man came to police attention after parcels containing the firearms were intercepted by the Australian Border Force.

"Please be advised that it is an offence to possess or use a firearm, pistol or prohibited firearm unless the person holds the relevant licence or permit. Further, it is an offence to supply, acquire, possess or use a firearm that is not registered," NSW Police said in a statement.

Gel blasters and other prohibited weapons can be surrendered to a participating firearms dealer or police station without fear of prosecution. A list of surrender points can be found on the crimestoppers website.