Firstly, I would like to suggest, that empty ammo boxes destroy themselves automatically, wont show up on the map anymore or at least a message that the box is empty. (like the notification that your rally point has been destroyed)
As a player that plays mostly engineers, it is difficult to maintain all structures and have an eye on which ammo crate can still provide. It would be much easier if I knew that they are empty.
Secondly, I suggest that the engineer gets points depending on the ammo actually given:
A mortarman recharges his mortar, empties the box and you get 15 XP. Another player recharges his BA rifle with 5 bullets and you get 15 XP.
yep, makes no sense, so it would be great if the empty ammo crates destroy themselves and then if the different types of ammo give you more or less XP points.
Also, it might be good if your engineers regain some construction points if you destroy your own weapons (AA guns, AT and MG nests), just as if you reuse those parts for new equipment.
from me 