Zayed Hussain Shaikh alias Kaju, suspected to have links with the Shakeel gang, was arrested with Nayeem Siddiqui alias John outside a hotel in Jogeshwari late on Friday night, they said.
A country-made revolver, a pistol and five bullets were seized from them, they said.
Shaikh had undergone a four-year prison term in an extortion case filed by a city businessman. Qayoom, a lieutenant of Chhota Shakeel who was arrested by the Crime Branch earlier in 2007, is an accused in the same case, police said.
The duo was booked under the Arms Act and remanded to police custody till April 4 by a court in Mumbai on Saturday.