EDIT: I’ve included some material drops in my calculation, it’s more like 60+ HE items from airdrops only.
This is something I’ve been doing on occasion when I don’t feel like grouping up.
Airdrops are a type of chest many people overlook. They often hang from trees/buildings and you need to shoot them to open. First 10 will also drop armor dyes for you. They drop 2 items that are always HE quality, and you can open them every 24 hours, like with other chests. Once we’ll get unified timers it will be even easier to farm them.
This is a map of all airdrops, the grayed out ones drop crafting mats instead of items. You can get the same view on https://division2map.com/ (hint: hit hide all to make the map readable) to have location descriptions and be able to zoom in. You will have to mark out the material ones yourself.
Note that there are 2 drops that are inside mission area. I’ve grayed out the one in Jefferson Plaza, as it is at the end of mission, but the one in air and space museum is at the very begging, so you can just run in, grab it and get out.
There are also decent amount of normal gear boxes near the locations, so you tend to pick up a lot if items overall. Best thing is that you don’t really need detection buff and there is very little combat involved, mostly just roaming packs on the streets.