SP Sunil Chowdhury said a large haul of firearms and ammunition was made during the raids at the clandestine arms unit of accused Aftab Alam at Lichubagan area of Baruipur.
Alam was arrested.
The seized arsenal included 18 pistols of 9 mm caliber, one 7 mm pistol, 8 unfinished 9 mm pistols, 100 cartridge shells, 250 semi-completed magazines besides lathe machine.
The place, the adjoining compound of Alam's house, has been sealed.
Police were investigating whether Alam was connected with an inter-state arms racket.