Businessman Jim Mansfield Jnr had a gun permit for his legally-held firearm revoked following a Criminal Assets Bureau (CAB) raid.
Mr Mansfield (47) was formally notified by gardai over the Christmas period that the licence for his Walther .22 handgun was being withdrawn over recent allegations relating to threats on his life.
The firearm was seized during a series of raids last January during which 31 different sites were searched as part of an organised crime probe.
Officers from the Emergency Response Unit, CAB, National Drug Unit, Fraud Squad and local detective units backed up by the garda helicopter were involved in the search operation.
Private residences and business properties in Dublin, Cork, Kildare and Louth were searched.
One of the properties was the Finnstown Castle Hotel, which is managed by the businessman.
It was the scene of an armed robbery last October, during which a 27-year-old night porter was tied up and threatened at gunpoint.
Two masked men, one of whom was brandishing a handgun, burst into the hotel in the early hours and eventually made off with more than €6,000 in cash.
Separately, in May 2014 a large bomb was discovered at the hotel, which forced the evacuation of a wedding. That incident was not linked to last January's raids.
Mr Mansfield is reported to have been formally notified that his gun permit was being revoked by gardai on behalf of the Dublin Metropolitan Region (DMR) West Chief Superintendent, who is based in Blanchardstown. The businessman is said to have told gardai that his reason for possessing the firearm was to protect himself. In September, Justice Minister Frances Fitzgerald introduced tough new laws regarding the issuing of gun permits.
The changes to licensing included plans for An Garda Siochana to establish a centralised system for restricted firearms, as well as new laws to monitor the number of 0.22 handguns being licensed.
"The new authority will be best placed to make an objective and independent assessment as to whether we continue to allow certain firearms to be licensed and result in a more transparent licensing system," said the minister.
"In the meantime, all persons who currently hold licences for 0.22-inch rim fire calibre handguns can apply to have those licences renewed."