The pre-order things call the weapons exclusive. I take that to mean that you cannot unlock them, and I hope thats true because I'm selfish. hahaha.
It would cause an uproar, especially about the machine pistol. It's unfair to the rest of the players that a select few get to have access to special weapons just because they had more money at the time.
@NHsports123: The items are meant as a fun bonus, you're supposed to pre-order so you can make sure you play the game on day 1 and thus gain an advantage over many other people. ( A whole 24 hours to play with a few thousand other people before the shelves get restocked)