Need ID of ammo boxes

I found in my collection some bigger ammo boxes and cans The plastic one is of 25mm Bradley ammo and the steel can also. But what is the other steel box for? Bulk transport of .50 cal. ammo? There no markings except stamped MFG number. The box is 449mm/12.8 inch wide, 345mm/13 inch high and 135mm/5.3 inch deep.

That first box does not appear to be US. The latches are wrong, so is the color. It might be German/Bundeswehr.