Officer Robert Barboza also will be suspended without pay for 30 days.
Deputy Chief Don Kenney says Barboza was charged in April by an internal affairs unit and later pleaded guilty to charges including gross neglect of duty.
Police say Barboza drove the vehicle home on March 17 at the end of his shift. The next morning he discovered the windows had been smashed and a rifle, about 15 rounds of ammunition and a police radio and charger were missing.
Police say Barboza was only authorized to drive the vehicle while on duty and park it on city property.
Barboza declined comment Saturday.