I don't understand loot system. Game is getting frustrating

[Soviet]

[quote author=Yoruichii link=topic=40508.msg222597#msg222597 date=1425055915]
Unfortunately, it is very unpredictable...5 days ago i've looted around 400k of "green" mats the same day, and nothing since this day after so many runs  :

Around 13 rags and I only get a raven and some hardened...
[/quote]
I looted 40m+ in 10 days