On this exact same load the last batch I made on October I had read that dipping the case neck in graphite powder can improve the consistency of the neck tension. So i tried this with 20 rounds. I was unable to chrono while shooting at PNTC but I saw a noticeable drop in impact deviating from my previous calculations. I re-ran the ballistics until I got the calculator to spit out the drop I was witnessing. It seemed to indicate a reduction in MV by about 55fps. I was surprised that a reduction in neck tension could have resulted in that much of a change, if that was indeed the cause.
It certainly makes sense that it would be slower with graphite, 55fps seems more than I would have guessed honestly but could be spot on.
I seat my bullets with a hydro press that reads in psi. I can tell you that the difference between graphite and normal is about 40 psi(estimating 2 thou of neck tension). Never chronod it though