You are aware that Drones are not from a Civilization that is the backwater of the Galaxy as Earth is? Therefore shooting down those Buggers CAN provide you with items you don't can manufacture in the current Situation or supplement your own stocks. As those are Drones they won't drop Rock or Ore but parts and Ammo. You may of Course wish to get less stuff from them to research and built it on you own. The simplest way around is just shoot them down and don't bother to loot them.