Here is a video that explains Gear loot drop, and how gear score works that makes sense.
- Each group of players that tag a mob reduce the loot chance, so if say 20 people are ungrouped that counts as 20 groups, where as 2 parties of 5 people each would count as 2 groups and the rate would be cut by that amount instead of 20.
- Gear score for drops on monsters and chests are water marked, meaning each gear slot and weapon type must drop at a specific GS for that water mark to increase. Farming lv25 elites as a lv50 will not get your GS of your range since those mobs don’t actually have your lv GS in their loot table.
- Loot chance on monster drop and from looting a chest PERK will increase the chance of you getting a next teir gear item. So from gray to Green, Green to Blue etc etc only so long as it can actually roll a high enough GS value to turn into Green/Blue/etc.
TLDR; Go watch the video its informative.