10 boxes right?
place 1 ammo from the 1st box, 2 ammo from the 2nd box, 3 ammo
from the 3rd box etc till the 10th box then weigh them
together.
each ammo shud weigh 10g. should the weighing machine show a "9"
in its last digit, it means its from the 1st box. if it shows an
"8" it means its from the 2nd box. if it shows a "7" then its from
the 3rd and so on and so forth
you're assuming the difference in due to the lighter box carries
a diff kind of ammo.