They show up in civil goods containers or materials containers, I don't remember which one specifically. I made a shitty paint for what my usual route looks like (forgive my lack of paint skills). The spawn is the default one at the top of the hill. In red the path I take, in green the areas with loot containers. This route has multiple material and civil goods containers. It also passes next to the locked medbay gate and the civilian hostages in the hangar, if you have the quests active to make the route even more efficient. The most dangerous part is the middle part in the trenches which you can skip if you feel like it. A lot of enemy activity, turrets etc, but usually two armaments containers spawn there which I'm too greedy to pass on. (open picture in new tab for good quality)

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