The find was made by gardaí investigating organised crime.
Two men remain in custody this morning after being arrested in Westmeath following the discovery of a semi automatic handgun.
They were detained after the vehicle they were travelling in was stopped and searched in the Rathowen area yesterday afternoon.
Gardai made the arrests in connection to organised crime investigation in the greater Dublin area.
They are being held in Blanchardstown and Finglas Garda Stations.