The 31-year-old man was detained by officers in the Horse Shoe pub on High Street at around 4.30pm on Sunday August 25, after allegedly brandishing the firearm in that pub and the Prince of Wales, also on High Street.
When the officers - who had been alerted by a member of the public while on patrol - found the man, he was also found to have a large quantity of cannabis on his person.
The officers arrested the man for possession of a firearm and possession with intent to supply.
A police spokesman said no threats were made and no one was injured.
The man has been bailed pending further enquiries.