Unfortunately a small rotor UAV, with BOD 1 and Max CF 1, cannot carry anything heavier than LMGs. You'll have to go Medium for heavier fire support. Such as:
RQ-31 Firefly
Body: 2
Armor: 3
Cargo: 0
Handling: 2
Autonav/Pilot: -/3
Sensor: 6
Seating: -
Entry: -
Load: 0
Speed: 60
Accel.: 5
Signature: 8
Fuel: 300PF EFC
Economy: 0.5km/PF
Chassis: Rotor Craft UAV, Medium
Street Index: 3
Availability: 3/72hrs
Cost: 44,572

Other Features: ED-1, Power Amps-4, Remote-Control Encryption Module-3, Remote-Control Interface
That's baseline for a spotter drone capable of being a fire support platform. You'd still need at least BattleTac FDDM and a Fixed External Hardpoint with the weapon of choice. That hikes up the price of the drone to ~80k, Street Index to 3+, Avail to 4/4d, etc.