The former lawmaker has been booked under the Arms Act. He has been taken for interrogation to the Quwarsi police station, the official said.
A team of the Special Task Force (STF) of the Uttar Pradesh Police raided the former lawmaker's house from Charra in Mathura around midnight.
The STF official said that the operation was based on a "conclusive lead" given by a gun racket runner, who told the team that he had sold a smuggled weapon to the former legislator.
The recovered pistol is a 9mm sophisticated 'Tauraus' made in the US, Inspector General (IG) STF Amitabh Yash told IANS, adding, "We are trying to dig deep into the issue."
The Tauraus pistol is said to be priced anywhere between Rs 4.5 lakh-5 lakh.
Mr Singh was accused of threatening a builder in 2016, beating up a police constable and vandalising government property in the past, besides being accused of intimidating a doctor.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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