I am having a problem with my Redding neck sizer die. It is giving me more runout than I would expect it should. Press is a RCBS Rockchucker. I am using an o-ring on the die so that it “floats”. I had heard that the o-ring can help to reduce runout. I have not tested it with the standard lock nut. Fired cases have less than 0.001” of runout on the neck. They have less than 0.001” variance in neck thickness as well. But when I run them through the die (it has a carbide sizer button) they come out sometimes with 0.0035” of runout. 0.003” is common. I removed the carbide button and runout was still about 0.00275”. I use moly powder when neck sizing. I cleaned the die with a q-tip and checked again and runout was still about 0.003”. So what might the problem be? I have heard that as runout increases so will group size. Is there any ballpark figure? Like if the gun shoots 0.5” groups with 0 runout what would group size be with 1, 2, 3 thousandths of runout? Thanks, Rufous.