On Wednesday, Bryan Christopher McManus, 56 and from Aileen Terrace in the city, pleaded guilty to possessing eight handguns, including one which was disguised as the removable handle of a walking cane.
He also admitted having a rifle, component parts of weapons, seven magazines and a quantity of assorted ammunition including armour piercing and expanding, or 'dum dum' bullets, designed to expand on impact.
McManus also pleaded guilty to conspiring with another person not before the court to convert imitation guns into firearms on dates between 1 September 2007 and 24 September 2010.
The weapons haul was recovered from outbuildings behind his house in Aileen Terrace in September 2010 and his lawyer said he had been modifying previously deactivated guns for several years.
The lawyer said police had alerted McManus to a number of threats on his life and after the last one, in 2007, the accused made contact with what he described as "certain elements" who might be able to provide him with protection.
He said McManus was able to reactivate a gun which was given to him by a man referred to only as Mr X, who then asked him to undertake other similar work.
The lawyer said McManus had become indebted to the people who had provided him with the weapon and 'things spiralled out of control.'
McManus told police that veiled threats had been made against his family and he felt that he was caught in a trap so he continued to re-activate firearms.
During interviews he said he believed that Mr X and his associates were members of the Real IRA who told him the guns were for defensive purposes in interface areas.
The defence lawyer said that McManus had initially seen the work of reactivating the weapons as a challenge to his engineering skills.
The defendant told police he was "the best toolmaker they would ever meet".
But eventually he botched some of the jobs and said he was relieved when he was caught.
He said McManus wasn't a member of any terrorist organisation and had been preyed upon by more sinister people and he wasn't able to say no to them.
Judge David McFarland adjourned the case until Friday and warned McManus that a custodial sentence was inevitable.