Gardaí have arrested four men and seized a firearm, a telescopic sight and firearm component parts in an operation in Crumlin last night.
The search at Captain's Road was carried out by officers from detective units in the Dublin Metropolitan Region.
Four men were arrested during the search.
They are aged in their late teens and early 20s and are being held at Crumlin, Sundrive Road and Terenure Garda stations under Section 30 of the Offences Against the State Act 1939.