The man came out of his own accord shortly afterwards and was taken into custody without incident.
"It has been confirmed that the firearm he had was a BB gun. Prior to leaving the pub the male had allegedly fired a couple of pellets inside however there is no indication that he had threatened or presented the gun at anyone at any stage," the statement said.
Police said it was a prime example of an unnecessary and dangerous situation involving a fake but highly authentic looking gun.
"Had this person not cooperated with police instructions but instead presented that gun in any manner towards them or other persons the response may have been drastically different, and the outcome potentially tragic."