Never used that powder but I am curious about the bullets you did use with it? Flash suppressant is like adding sawdust to a powder,,, too much will always end up in bad results. ( like unburned powder) OR the flash suppressant burning much dirtier.

I also question the crimp. I have seen blowback with the brass ending up real dirty, because the powder was not burned up before the bullet leaves the chamber. A good crimp is needed always.
I am not questioning or denying the facts that some powders seem to be more dirty than others. Heck Unique advertised, that it was cleaner burning with the newer formula.