Three men are being questioned over the seizure of a handgun and ammunition.
The weapon was discovered when gardai stopped and searched two cars near Dublin Airport.
The search took place on the Swords Road, near the Coachman's Inn, shortly before 1.30pm on Tuesday.
The three men, one aged 33 and two aged 35, were arrested and detained at Ballymun and Santry Garda Stations.
They are being held under section 30 of the Offences against the State Act.