Expect the Modern Warfare III Gunsmith to be an approachable, familiar, and vastly customizable weapon builder. Its goal is to make nearly every weapon in the game a true extension of your personal playstyle.

As with MWII, building your weapon involves leveling up the weapon by obtaining Weapon XP (WXP) and unlocking modification slots to add attachments to your weapon. These attachments enhance your weapon’s performance. You can add up to five attachments to most weapons.
MWIII Aftermarket Parts: Some weapons have Aftermarket Parts, a modification system that dramatically after a weapon’s functionality and character. These unique upgrades are earned through weekly in-game challenges once a weapon reaches its max level.