Rocket components, pipe bombs, shot guns and ammunition have been seized during a crackdown on the Real IRA.
Five men and a woman were arrested on suspicion of membership of an unlawful organisation during the operation by armed members of the Special Detective Unit.
A senior source said the arrests are linked with on-going investigations into dissidents once led by murdered terror boss Alan Ryan, whose first anniversary was marked last weekend.
"This was a significant capture," he said.
"These are significant players in the whole dissident fraternity in Dublin.
"They would have been heavily connected with Alan Ryan."
The five men were arrested when officers stopped two cars on the N11 in Co Wicklow this morning.
The five, who are all aged in their 20s, are being questioned at various garda stations across the capital.
Firearms, assorted ammunition and component parts for explosive devices were found in follow up searches on the outskirts of Dublin's north inner city.
Four vehicles were also seized and a woman in her late 20s arrested for membership of an unlawful organisation.
She is being quizzed at Ballymun Garda Station.
All six can be held for up to three days under the provisions of Section 30 of the Offences Against the State Act.
Detectives are awaiting the results of forensic tests on the cars and ballistic tests on the firearms and explosives, which were described as pipe bombs and components of rockets.
Ryan, 32, was gunned down near his family home in the Grange Lodge estate in Clongriffin on September 3 last year.
A volley of shots was fired over his coffin at his funeral in a show of strength by the Real IRA.
Last weekend hundreds of people attended a major one-year anniversary commemoration at his grave last weekend, including a colour guard with paramilitary trappings.
His headstone has been vandalised the night before and two suspect explosive devices found at his grave earlier this week.
The incidents are linked to an escalation in a feud between dissidents in Dublin and the gangland criminals believed to have been behind Ryan's murder.