Gardaí have seized a semi-automatic pistol, rounds of ammunition and €153,305 in cash in Dublin.
The seizure followed the planned stop of a car in the Balbriggan area of the city on Monday.
The driver of the car, a man in his 40s, was arrested and he remains in custody.
Gardaí say further evidence was recovered during a number of follow-up searches.
Assistant Commissioner Cliona Richardson said: "The seizure of this firearm and ammunition has no doubt saved lives, and the removal of significant amounts of cash not only removes ill-gotten gains from the hands from criminals, but deprives them of money they would have used to fund further criminal activity in our communities."
