This should be in your manuals. What manuals do you have?
Max case length=2.015 inches.
"All answers that I have is that one must ensure that at least one third of the bullet is seated in the catridge case."
Never heard this before, maybe because it is wrong. The rule of thumb is that one bullet diameter be seated into the case. That would be .308 inches be seated into the case of your 308 Win.