Odd, that.

"Mil Contract" ammo tends to be a little more cryptic in the headstamp department, usually NOT showing cartridge designation, for instance.

The 150gn bullet thing is another thing. What "proper" military ordnance system would purchase "odd" ammo for general distribution. By "odd" I mean ammo that has a completely different trajectory and ballistic performance from that around which EVERY weapon in that caliber in the inventory was built.