The explosives were packed in a polythene bag which was found dumped in the garbage van parked near a temple in Sai Samarth Nagar area, they said.
Devlali Camp is a major Army centre and has been on terror radar.
Police said out of 28 cartridges, 21 are live and another is of a Light Machine Gun (LMG) whereas the empty cases are used to keep SLRs and LMGs.
Maharashtra ATS had arrested LeT terror suspect Shaikh Lalbaba Mohammed Hussain for allegedly conducting reccee of Army's Deolali camp, Maharashtra Police Academy (MPA) and Police Commissionerate in Nashik in 2010, allegedly on instructions of Mirza Himayat Baig.