These follow up searches were carried out in two cells.
Gardaí say they've prevented an attempted murder in West Dublin.
A gun was found in a vehicle on Tuesday night as part of a planned search on Rowlagh Avenue in Clondalkin
Follow up searches were carried out in two prison cells in Portlaoise Prison as well as 18 areas in Dublin.
Two men in their 30s and 40s were arrested at the scene and brought into garda custody.
300 gardaí were involved in the operation.