Four men are still being questioned after gardaí foiled what they say was an attempt to kill a member of the Hutch family as part of the ongoing feud.
The men - two brothers, a former British army soldier and a dissident republican - have had their periods of detention extended and are in custody at various Dublin garda stations.
They are being detained under anti-gang legislation and can be questioned for a week.
Five weapons including a sub-machine gun, a semi-automatic pistol and two handguns are being examined by ballistics specialists.
The weapons were loaded and a silencer was also recovered with one of the firearms.
Gardaí say the arrests and seizures are part of an intelligence-led operation by the Drugs and Organised Crime Bureau into the activities of the Hutch-Kinahan crime gangs.
The investigation also involves an international dimension and the Assistant Commissioner in charge of Special Crime Operations is meeting a senior officer of the UK's National Crime Agency in Dublin.
John O'Driscoll said the focus on the gangs is "unrelenting".