I guess that in secret facilities, like the one of "Tania's Escape", the staffs
won't abandon the facility to bring ammo, and moving a large amount of ammo call
too much the attention. Secret Facilities would have ammo vending machines, so
the staff doesn't need leave them post because the ammo ended.

If needed, there could be also a pharse "Insert you Staff ID Card or insert a
few coins" before using this machine. If tux could get a Staff ID Card item, he
could gain some ammo for free, but limited to tux don't use this to don't pay
for ammo anymore.