South Korean 30-06 box


I was recently shown this South Korean .30 cal M2 box filled with M80 7.62mm NATO cartridges headstamped P S 7 6. There is a neatly cut piece of corrugated cardboard inserted in the box to prevent the cartridges rattling around in the box. I was told that this is how the early South Korean 7.62mm NATO ammunition was shipped to the US. The box label is shown in Chris Punnett’s 30-06 book but the contents were not known. Can anyone confirm what the original contents of this box were? I suspect that the Korean box was refilled with NATO cartridges at a later date as I find it hard to believe that incorrectly labeled boxes would be allowed to leave the factory let alone be exported. But stranger things have happened …