I'm using Lee dies for 308. I made a dummy round with each bullet I'm using in same brass I'm using at 2.810. When I put the die in and it is clean I run the top down until it touches the bullet tip. Then after powder charge I load bullets and they range from 2.80 to 2.812. The 2.812 I can tweak a little and get down to size. Is it the spring I feel in Lee die that does this. I have RCBS dies and set them for 178 Amax as I don't load a lot of them. It varies on one or two by a thousand but not every one. Or is this best I can expect? I measured some factory Federal and Remington ammo in 243 and they vary by 3 thousands. Using Lyman vernier caliper and Frankford Arsenal digital caliper to double check and it still reads the same. I do prefer the Vernier caliper.