What Causes Error in Primer Seating Depths!?

The purpose of this video is to describe the main factor in what causes error in primer seating depth in primer seating tools that are shell holder dependent. The main factor is the brass' rim thickness. Variations in brass rim thickness will cause variations in primer seating depth. When comparing certain shell holder tools, the Primal Rights bench top primer seating tool performed significantly worse compared to the PMA hand held primer seating tool (double the amount of error) and the Lee ACP. The tool that was not shell holder dependent, Lee ACP (with modification), performed the best and seated primers with almost no error. Shooters needing to use hand priming tools such as when they load at the range, can use primer seating depth as a proxy measure for rim thickness and then remove brass pieces that are out of spec. When priming where adequate space is available, it is recommended that you use a primer seating tool that is not shell holder dependent such as the Lee ACP (with modification).