One of this year's biggest hooks in Call Of Duty: Modern Warfare 3 is Weapon Proficiencies, which essentially allows you to collect and earn "mini-perks" for your weapons. Proficiencies allow you to improve your performance with small incentives, such as reduced kick or sway. Each additional attribute is unlocked via a separate XP progression bar attached to each weapon.

As Sledgehammer co-founder Michael Condrey explains, "go earn it".