Not only will you be able to level up your overall rank in Modern Warfare 3 multiplayer, but you can now level up the weapons which you use. In addition to the obligatory weapon camos and attachments, Weapon Proficiencies allow players to enhance their weapons with new attributes, such as decreasing the weapon's sway or kick when firing.
The latest Modern Warfare 3 developer diary covers everything involved with the game's gun progression, so those looking to pick up it up in two weeks should definitely check it out.
