I am having trouble figuring out how to knock back the shoulder of some twice fired .308 Lake City brass. I just installed a new Redding type S bushing style full length sizing die on my (don't laugh) Dillon 550. I threaded it down to the shell plate holder just like the instructions said to. My flash-fired brass head-space measures 1.6250" averaging ten rounds. I want to take this down to 1.6230 or at least 1.6240 to be one or two thousands off. I believe that is right? After re-sizing ten rounds that were all from 1.6250-1.6260 I ended up with some that were 1.6230 and others that had grown to 1.6275. What exactly is it I need to do to make this adjustment? I cannot crank the die itself down anymore or it will crush the shell holder. I have only been attempting to reload precision rifle rounds for a few months so I just don't have the experience to know what to do next. Surely this is not that big a deal, can someone give me the answer or at least some suggestions?