There's a mechanic in the game where a human npc loots their fallen pals - "they don't need it anymore, but might be useful for me"
From my observation most if not all human factions do that.
I found out that when they do it, they take everything from a body (except for some consumables). That includes armor and, albeit rarely, even detectors.
Also, I haven't seen them loot bodies outside of their "group" (even from the same faction), so you need to remember that.

I'll try to make it short and easy to understand:

• Find a group of human enemies (it can be friendlies, but we don't wanna tarnish our reputation, right?);
  
• Engage one of them stealthily (you can do it loud, but you'll need to wait till their agro cools down and sometimes they can move far enough from a body so they won't loot it);
  
• Hide from their search if needed. When they go back to idling they'll loot the dead one if it's in their field of view;
  
• Wait till they finish looting the body;
  
• Kill the looter;
  
• Enjoy "your" armor.

When npc takes a weapon from the body, it gets reloaded.
If you can pull it off, you can put empty weapons in the body they are going to loot and all of them will be loaded. Extra ammo, heh. But it's not easy to do and can mess the whole looting process so I wouldn't bother doing it.
But beware!
Sometimes, it can lead to unexpected results: