A Bexley man, 21, has been charged after allegedly attempting to buy a Glock pistol and ammunition online.
The arrest was made in a Rockdale car park by strike force detectives investigating the supply of illicit drugs in the southern suburbs.
State Crime Command's Drug and Firearms Squad established Strike Force Narus in September this year.
"During the course of the investigation, investigators received information suggesting a man was attempting to acquire a firearm," a police spokesman said.
"Following extensive investigations, strike force investigators arrested a 21-year-old man at a car park at Rockdale about 11am on Monday, September 16.
"Shortly after the arrest, detectives searched the man's car and allegedly located prescription medication.
"The Bexley man was taken to Kogarah Police Station and charged with attempt to acquire firearm (pistol) without licence or permit, attempt to acquire ammunition for firearm without licence, and possess prescribed restricted substance.
"Police will allege in court that the man arranged to purchase a Glock pistol and ammunition online.
"He was granted conditional bail to appear at Sutherland Local Court Tuesday, October 15."