Originally Posted by Gene
Try this: Size the case once, then turn it 180 degrees in the shell holder and size it again. Do same with the seater; lower the bullet about 70%, turn in the shell holder and lower it to desired OAL. Theory is that increases consistency all around. I have no way to prove this theory.
+1 on this. I go a little further though. When sizing I will lift the ram just enough to free the case and rotate the case about 1/4 turn 4 or 5 times bringing the ram back down each time. I do the same for seating a bullet.
I have proved this works many times by measuring runout on rounds I loaded with this method and rounds loaded with one sizing and seating stroke. Using this method I get my rounds ALL within .003 with the vast majority .001 or less. If I occasionally get a .004 I can usually put it back in the seater and bring the ram down 8 or 10 times rotating it just a little each time and bring it to .003 or less. This is with a long 338 Khan, shorter cases should work even better.
One other thing is I do not use an expander ball. They tend to put stress on the neck / shoulder when pulled out.