Building your loadout in Call of Duty: Modern Warfare 3 is the same as crafting your build in an RPG. Which weapons and perks you take can completely change how you play and what role you should take in any given match. Typically, you are restricted to equipping a primary and secondary weapon, but previous titles included a perk that allowed you to double up on primary weapons to essentially play double duty. That perk, Overkill, isn’t in Call of Duty: Modern Warfare 3, so you will need to look for a different solution to get two primary weapons this time around.
How to equip two primary weapons
Instead of the Overkill perk giving you space to carry two primary weapons, Call of Duty: Modern Warfare 3 introduces the Gunner Vest. This is a piece of gear rather than a perk, and can be unlocked when you hit level 20, or you can use the Overkill vest when you hit level 50. The Gunner vest lets you start with more ammo, reload faster, and, most importantly, equip two primary weapons.
Once you’ve unlocked the Gunner Vest, you can equip it by going into the Weapons tab in the Multiplayer menu, editing your loadout, and selecting the Vest option above your primary weapon. Once equipped, you can slot in a second primary instead of a secondary for that loadout.