Police said the two were nabbed during a vehicle check at Vaigai Kodi and the weapon was recovered from the car
The two were involved in several cases, including kidnap and extorting money from people in and around kanyakumari district, they said.
Police said strict vigil would be maintained on the vehicles during night, ahead of the coming assembly elections.
Cases had been registered under various sections of the ipc against against the duo, police said.