Gardaí have carried out three raids in Drogheda, Dublin and Limerick in the past three days.
Today, officers investigating organised crime stopped a car in the Main Road area of Tallaght and seized two semi-automatic 9mm pistols along with 25 rounds of 9mm ammunition during a search of the car.
One man, aged 36, was arrested and is being held at Crumlin Garda Station under the Offences Against the State Act.
Also today, National Crime Bureau officers searched a premises in Drogheda, Co. Louth, and discovered cannabis resin worth more than €40,000.
A 34-year-old woman was arrested on suspicion of drug trafficking and she is being questioned in Drogheda Garda Station.
Yesterday, Gardaí investigating organised crime seized drugs and weapons worth more than a million euro in Dublin.
Officers from the Garda National Drugs and Organised Crime Bureau, supported by the Special Crime Task Force, searched a premises on the Greenhills Road in Tallaght.
They seized two semi-automatic .22 calibre pistols and 20 rounds of ammunition, along with a large quantity of cannabis, cocaine and diazepam tablets worth more than €1m.
A 49-year-old woman has been arrested in connection with the raid and is being detained at Tallaght Garda station.
In a separate development, a gun, shell casings and ammunition have been removed following a search of a halting site in Limerick City on Wednesday.
The search was in response to reports on Tuesday that a firearm was discharged at the site in Southill.
No arrests have been made and investigations are ongoing.