How do you unlock attachments in warface?

Answer 1

You have to earn VP, you can do this by playing co-op or versus. Before you start the game there is a vendor icon, click on it there will be three different kind of categories to choose from, Weapons, Armor, and Attachments. Vp is like experience, you need to unlock the weapon before purchasing the item that you want. You can not choose a specific item to unlock except the three you see, once you unlock that item, the game will choose another random one by common, uncommon and rare weapons, armor or attachments which other one your trying to unlock. The more common you unlock the less of a chance you will get a common, if you unlock all common items than you will only receive uncommon and rare.