In normal operation there is a differnce in charge weight which demonstrates the effect of a change in opearting manner. The process of loading may tend to eliminate variations in manner of operation which has always been emphasized in powder measure operation.
I notice a 1/10 or so variation in the chg wt from time to time in weighing using a given bushing or slide. I supose this to be moisture as the difference is not observed when shootnig.
All this is exclusive to lot to lot variation. For my short line loads I have 3 bushings which might be referred to as light, normal & heavy. The wt dif in these are .15 grain. When starting a new lot of powder the appropriate bushing is determined.
I pass this along as food for thought. I am interested in hearing of other's experience in this area.