How in the world can you figure that the .308 has a flatter trajectory than the 30-06 with the same bullet weight and pressure level?????
Are you aware that the .308 is simply a 30-06 case that has been shortened? Apparently you really don't know much about rifles and their cartridges. All other things being equal-the 30-06 will be 150-200 fps faster than the .308!