Two men are being questioned by Gardai in connection with an investigation into dissident republican activity.
The swoop is part of on overall increase in activities by anti-terrorism Gardaí ahead of the visit of Britain's Prince Charles next week.
Just before midday yesterday, Gardai on traffic enforcement duties stopped a car at Glenfarn on the N16 Sligo to Enniskillen Road at the Kiltyclougher Junction near Manorhamilton.
On searching the vehicle they discovered a pistol and suspected component parts for explosives.
The two were arrested at the scene and are currently being detained under Section 30 of the offences against the state at Manorhamilton Garda Station.
The scene was closed for a technical examination yesterday afternoon and the assistance of the army EOD was requested.
Security has been stepped up in the Northwest with the Prince of Wales and his wife Camilla due to visit Sligo on Wednesday next.