If you have the Gigawatt or Supernova variants, use them. The Supernova reduces the overheat penalty and increases fire rate. Do not use the Shocker ; it reduces damage.
Most CODEX-based versions include the base game plus all DLC packs (Havoc, Ascendance, Supremacy, and Reckoning) and the Exo Zombies mode, which are often expensive or difficult to bundle together in retail stores. call of duty advanced warfarecodex better