A pipe bomb, two shot guns and ammunition have been seized by detectives targeting the activities of dissident republicans.
Gardai from the Special Detective Unit, assisted by local units, discovered the weapons during a search of an open area in Kiltipper, Tallaght, as part of an ongoing operation.
A Garda spokesman said no arrests were made and investigations are continuing.
The Defence Forces said its bomb disposal team was deployed to Tallaght at 4.50pm on Thursday.
A spokesman said the weapons were made safe and handed over to the gardai for their investigations. "The scene was declared safe at 7.45pm," he added.
Army bomb disposal experts were later called out to Ronanstown where they made safe a viable improvised explosive device (IED).
The team arrived at the waste ground off the Fonthill link road at 9.10pm in response to a request from gardai.
A spokesman said no controlled explosion was carried out and the device was handed over to gardai for their investigations.
The scene was declared safe at 10.45pm.
The incident brings to 159 the total number of call-outs so far this year.