.308nate--Glad you figured it out and thank you for sharing your finding. Makes sense in retrospect.
In the beginning God created the heavens and the earth. Genesis 1:1
"And can the liberties of a nation be thought secure when we have removed their only firm basis, a conviction in the minds of the people that these liberties are the gift of God?" Thomas Jefferson - Notes on the State of Virginia
While we are on the subject, I also had trouble with factory dies failing to bump the shoulders on a couple of 308 custom chambers. I tried bumping the ram then going another 1/2 turn to no avail. I finally shaved a little off the shell holder which fixed the problem. The problem with the 338/408 is different. The dies will bump the shoulders but will not resize the body enough to allow smooth extractions with repeated firings. The problem is being looked at as we speak.