I'm perplexed, and could use some of the brain power here.

I randomly chose 5 bullets from a box of .308 SMK 175's. To my surprise, they all measured identical on the comparator.
But when I loaded these 5 bullets, I got 3 different CBTO measurements, a variance of .005 shortest to longest.
So my question is what else can cause this?
I'm using a Forster Ultra Seater die, once fired LC brass trimmed to 2.005, RCBS Rock Chucker press. I checked to see that the die was not loose.
The only thing I can come up with would be some variance in the brass as it sits in the shell holder. Would this be a viable explanation? Could something else be causing it?