Yeah to get the exotic gun " ...you would need multiple Black engrams" so if black engrams drop gun pieces unless you have black engram 1-2-3... each engram I get will drop a random piece. And more exotic guns they can't even balance the exotics that are out now why in the world would they create 5 more non dlc exotics that they would have to balance, test, do art for and would be forced to add more vault space because the number of people complaining about vault space would go even higher. Another thing we already have exotic bounties that drop randomly then you have to do other steps to obtain the exotics so I personally don't think "Black engrams" will be implemented in this game and in the miniscule chance they are it won't be like this. Tl;dr It's not gonna happen reasons above