Primary weapons are your main weapons in Call of Duty®: Advanced Warfare, and their effective ranges largely define them. Using the proper weapon for the engagement ranges you expect on any given map is extremely important.
Keep in mind that Exo movement has shaken up some of the traditional Call of Duty® weapon roles. Exo movement speed can compensate for the sluggishness of Heavy Weapons, or emphasize the close-range power of SMGs and shotguns. Assault rifles remain potent general-purpose weapons, and sniper rifles gain the highly relevant and useful ability to one-shot kill targets out of mid-air.