Michael Oliver, 25, was refused bail on Wednesday after being charged with firearms offences following a raid at his home on Fowlers Road.

Documents tendered to court said Lake Illawarra Police District's target action group were tipped off that Oliver was allegedly in possession of a shortened gun that was stored inside a shed at his home.

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Police documents said officers went to Oliver's home on Tuesday about 1.45pm to search his property, where they found a black bumbag in his rear shed.

Police found and seized a .22 calibre single shot bolt action shortened rifle, mobile phone and a plastic releasable bag containing 0.67 grams of methylamphetamine, allegedly belonging to Oliver.

Oliver was arrested and taken to Lake Illawarra Police Station where he was charged with possessing a shortened firearm without authority; not keeping a firearm safely; acquire firearm subject to prohibition order; acquire ammunition subject to prohibition order and possessing prohibited drug.

Oliver had a firearms prohibition order imposed on him in 2018 which prevents him from acquiring, possessing or using a firearm, firearm part or ammunition.

In Wollongong Local Court on Wednesday, Magistrate Susan McGowan refused to grant Oliver bail due to his firearms prohibition order and the strength of the prosecution case.

"A custodial sentence will flow if he is convicted and his [criminal history] does not help him," she said.

Through his lawyer, Oliver denied owning the gun and said it could have belonged to someone else as the shed was a common room.

He said someone else had been sleeping in and using the shed at the time of his arrest.

Oliver also denied the mobile phone belonged to him.

He will reappear in court on April 14.