Man 'foolishly' used rifle to scope police

A man who allegedly used a bolt action rifle in Sydney's inner west to scope out a police operation nearby was "foolish" and drinking at the time, according to NSW Police.

Officers on Sunday night received calls from concerned residents who could see the 47-year-old man brandishing the rifle in a Rozelle apartment after 11pm.

The man was looking through his rifle's scope at a police helicopter which was monitoring a separate incident unfolding on the water nearby.

Local boat owner and good Samaritan David Hannon had come to the aid of a struggling swimmer some 200 metres offshore in Balmain Harbour.

But Mr Hannon was forced to abandon his own vessel by jumping into the water after the younger man became aggressive and allegedly assaulted him.

"When we were heading back to shore he was quite passive but then he started kicking me under the chin and side of the head," Mr Hannon told ABC radio on Monday.

"I decided I was going to take my chances with the bull sharks rather than this crazy."

The 23-year-old man from Guildford then took off in what Mr Hannon describes as "the slowest getaway boat" ever - his 80-year-old "putt-putt".

He was subsequently caught by police and charged with a number of offences including assault and unauthorised use of a vessel. Police say it is likely the man was affected by drugs.

The Rozelle man caught wielding his rifle has been charged with handling a firearm under the influence of alcohol and not keeping the firearm or ammunition safely stored

"This person made a very foolish decision to use the scope on that rifle to have a look at what was going on in the harbour, where the police launch and PolAir were out," Acting Superintendent Sam Crisafulli told reporters on Monday.

He was granted bail and is scheduled to appear at Downing Centre Local Court on April 27.