The ammunition was manufactured by the Ammunition Factory Khadki (AFK), police said.
"We have arrested the sharp-shooter identified as Sadiq Bengali and his aide Rihan Sayyad, both residents of Lonavala," Sunil Ramanand, Joint Commissioner of police said.
Acting on a tip-off, police nabbed Bengali and Sayyad from Swargate area of the city and upon search, arms and ammunition were seized from them, he said.
Bengali has several cases registered against him and he was also allegedly involved in an incident of firing on film-maker Mahesh Bhatt in 2006.