The ammo crate that Assault can get is not only the best in slot almost 100% of the time, as it allows Assault to get both ammo and bandages, which devalues both medic and support.
My proposal is to remove the crate from the Assault toolkit and instead give assault players the ability to use a new armour type that gives them +2 primary magazines and +2 bandages.
This allows assault players to still have the option of extending their ability to survive solo, as well as meaning that assault players would still have to go to support mains or call in a resupply to refill ammo, gadgets, grenades, and bandages, as well as giving them less overall bandages than they would have with an ammo box.
The armour could be called "expeditionary armour", and have +2 primary magazines and +2 bandages compared to heavy, and the same or lower movement speed, but with the durability of light armour