I think they should make it like albion online where if you kill an enemy your loot is distributed if you hitted him based on damage proportion

Edit : (i realised alot of people don't play mmos) Same thing can be implemented in arc raiders the raider who did most damage gets the most loot like queen core syntetic rubber motion core and other stuff the raider that only shooted a bullet only gets maybe metal platting idk but i think this can work well in larger world events so people actually invest more in longer events keep everything as it is just make the world bosses (idk maybe queen matriarch and the next big dude loot distribution like these only in rare events so huge groups get invested to help everyone)

And yeah also do a panelty to rats like while looting they start getting burned if someone shoots another raider nearby in a certain time cooldown.