keep in mind as well everyone that there are limited slots in your game weapons inventory. So don't go transferring over absolutely everything at once, because the game will force you to sell. Transfer a few and then use the game stats to decide what to sell, or use the item stats on re.net before you transfer so that you can keep them. I have for example, 2 M924s, exactly the same, except one has 2 more customization slots. Some have only slight differences, some major. There's a ton of options, but so many weapons that my screen turned red when I transferred them all lol. There's 24 slots plus the three you have currently equipped, so you can have 27 weapons in the game at one time.
EDIT: You can buy additional weapon storage from the in-game store with BP.