I've taken the advice of members of this board, especially Kirby Allen's, and have gotten my runout down to .001" on the necks of my FL sized 30-06 brass. It's the runout after seating which has got me stumped. Some facts to follow: -Winchester brand 30-06 brass, fired 4-5 times. -Primers punched out via a seperate Lyman Universal decapping die. -Sized with Forster BR dies so shoulder is not set back but just touched. Cleaned up the sizing die very well to make sure accumulated crud was not introducing variances. Sized the case without the expander button and checked runout which equalled only .0005". Did this to see if the expander button did/did not introduce runout. Once I sized the cases with the expander button set as Kirby Allen suggested, I was getting a max of .001" runout. -Concentricity device is the Sinclair. -I've really focused on cleaning up the necks with 000 steel wool inside and out. -Neck thickness varies from .001" to .0035" thick. This may be the varible I'm lookig for! -Device I use to measure thickness is the Sinclair MIC-4 thickness gage. -Neck length is trimmed to 2.484" via the Forster trimmer and chamfered with the Lyman VLD tool. -I'm using a Forster Ultra seater die. Nothing unusual about how I have this set. -OAL is about 3.556", or about 1/2 the neck has bullet bearing surface in it. Any suggestions on what I could do to get rid of the runout I'm getting at the seating station which runs upto .005"? I'm getting stuff which runs as low as .0015".