I am sure psychologists all over the world have a ball with the pairing of the words evil and black
Interesting. I do believe that "evil black assault rifles" was either coined by the left to demonize such things, or it was made tongue-in-cheek by gun owners in reaction to such demonization (possibly using their own terms, I don't know). If anything, given the characteristic nature of the left's policies, I'd say there's probably some truth to any psychologist's musings.
As for bigotry against guns... I like evil black rifles and pretty clad rifles (or pistols). Likewise, I hate the same: I'm absolutely bigoted against certain gun types, because I don't like them. That is, assuming we're going to start brandishing the term "bigot" around like the national media has been swinging "racist" for the past year. I don't think doing so is such a good idea; it weakens the meaning of the word to inaccurately ascribe it.