"Engies don't need to carry the ammo pack in their utility slot because the ACE device that drops turrets can also reconfigure to drop ammo packs by pressing 'B'. When you press 'B' you'll see the green outline of a turret switch to a green ammo box. These ammo packs last longer then the base one that's in the utility slot but don't receive benefit from relevant certs. However, since certing into the ammo pack doesn't fuckin help at all, there's no point in carrying an ammo pack instead of the healing syringe thing or explosives or something."