I have a Herters resizing die which I use regularly. I resize the casings and then I decided to case gauge them. They all fit the case gauge fine. When I seat the bullet (Berry RN 230 grn) I case gauge them again. I will gain approx. .001-.002 in diameter. The "bulge" occurs near the head of the cartridge. They stay under the recommended size in Lyman's #3 loading manual and I also "plunk" test the rounds. These are range rounds so they could have multiple firings. However I have noticed this in once fired rounds. My COAL is 1.250 using W231. What causes the cases go grow?? Is my woes coming when I am seating the bullet by pushing down on the projectile or possibly a worn carbide seating die??