Face of Nation : Officers from Police Scotland and the National Crime Agency Organised Crime Partnership (OCP) recovered the haul at about 14:00 on Thursday.
They had received intelligence and had a warrant to enter the building in Northpark Street.
The pensioner is due to appear in court at a later date.
Ian Thomas, the Scotland branch commander of the National Crime Agency, said: “This was a significant seizure of weaponry that had the potential to cause untold damage on our streets.”
He said the agency was “determined to tackle the flow of illegal firearms into Scotland and protect our communities”.
Police Scotland said a report had been sent to the procurator fiscal.
A spokesman for the force said: “Operations such as these disrupt criminal activity as well as addressing the concerns raised by local people.
“Crime has such a detrimental impact on local areas and I would like to reassure people that we will continue with these proactive operations, demonstrating our commitment to ridding communities of crime and its associated impact.”
The OCP is a joint investigative team involving Police Scotland the National Crime Agency.
