"What if it was 06? How would you tell the difference between 1906 and 2006?"
Frankford Arsenal closed in 1977.
And, no Government arsenal or munitions supplier was still manufacturing .30-06 ammunition with a gov't headstamp in 2006.
"Oh and am I correct in assuming the the bottom of each letter or number is oriented towards the primer?"
Depending on the specific time frame, generally the letters designating the manufacturer have the bottoms oriented toward the primer.
The month of production, IF there is one, often has the right side of the number towards the primer, while the year either has the left side towards the primer OR the top of the numbers towards the primer.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.