I had some just like that in some 30-06 I got from a guy on the CMP Forum. They were mixed in.
I normally can fund them on here
http://www.cartridgecollectors.org/headstampcodes
Looks like that 7.62x51 German DAG ammo that SGammo was selling . The headstamps were milled off because of some euro export law banning military ammo sales. By the looks of the case neck,(kinda blown out) it looks like it was fired in a .308 with "really long" headspace or from a rifle chambered in a different caliber then the ammo, maybe a 30.06 or 8mm
What is the neck diameter? Here is a 6.5mm Carcano next to a 7.62 Nato. There was also a 7.35mm Carcano, just a 6.5mm blown out but I don't have a sample handy.