I sent the link to NatoDave and he is thinking it looks an awful lot like a similar round with a 10 70 headstamp. Perhaps it is Bulgarian. He should be along later.
I just went back to my logs and checked. The primer crimps and seal colors on my Czech(?) rounds are different than the round posted above. I nod to David on this one.
Alex, there have been some short articles published on some of the odd ammo found in Cambodia. Some might be found linked to the IAA Forum. I will have to dig to see if I can find any here. I might not be remembering correctly, but I believe the calibers were .30-06, 7.5, 7.62, 7.65 MAS pistol, and 9x19.