OK, got the pix...
I THINK what I'm seeing on the head stamp is Isralie characters, but I'm not 100 percent certain about that, but it could also be Soviet or Yugoslavian characters, but the lighting is a little tough and I don't have a manipulation program on the computer here at the office.
The dimensions look similar to either .308 or 8mm Mauser -- it's kind of hard to tell the exactly length on your engineering scale given the fact that the picture has been taken at an angle.
The headstamp marking practice is a little odd for Yugo ammo, which is another thing that makes me think it's Isralie.
It's rimless, correct?
I'm still thinking .308 or 8mm Mauser, with it being more likely that it's .308 given that the case is about 2 inches, or 48mm, long, and the .308's case is 51mm in lenght.