Villagers barged into the house of CPI(M) leader Tapan Ghosh at a village in Garbeta police station area and discovered the mini-gun factory and informed the police.
Security forces found 1,000 rounds of ammunition, twelve .99 mm pistols, 2 rifles and a hand-made pistol from Ghosh's residence, sources said.
The CPI(M) leader and his family had left the house on May 12, a day before the Assembly elections results were declared, sources said adding that the only occupant of the house was the aged father of Ghosh.
Four guns were also found in Angua area in Kotwali police station area, eight from a field in Boita area under Jhargram police station area and two from Charka area in Keshpur police station limits, sources said.
At New Town, adjoining Kolkata in North 24 Parganas district, three firearms and 26 rounds of ammunition were found from the bank of a canal, sources said.