I have been running the dlc's and seem to only be finding whites in gun chests. I will find a couple of blues and a seldom purple after beating the bosses of the dlc but throw some blues into some gun chests every once in a while. Its kind of frustrating. I have gotten one orange on my second play through.
First play through I found like 3-4 oranges, then farmed the dj for the bee shield and thats the only orange i have seen in like 40 hours of play time