NSW man pleads guilty over music video gun

A man has pleaded guilty to possessing an unregistered air rifle after he allegedly used the gun as a prop while filming a music video on a suburban Sydney street.

Paul James Nicholson pleaded guilty to the charge of possessing an unregistered firearm in a public place at Newtown Local Court on Tuesday. However, his film-making companion Gawain Keith McGrath pleaded not guilty.

The 38 and 41-year-old were arrested in Faversham Street, Marrickville, in the early afternoon on June 17 following reports that a man was in the street armed with a gun.

Police say the pair were using an air rifle while filming a music video.

Court documents state the firearm was a "Daisy .177 calibre pump action air rifle".

On Tuesday, Nicholson's defence lawyer, Jack Tyler-Stott, requested a "lengthy adjournment so that a (mental health) report can be obtained" in accordance with the Mental Health Act.

Both men are on bail and will return to court next month.