The RCBS Case Master Concentricity Gaging Tool is a precision measurement instrument designed for serious reloaders who demand accurate concentricity readings of their ammunition cases and loaded cartridges.RCBS Case Master Concentricity Gaging Tool (Model 87310)Precision measurement of case and bullet runoutEssential tool for quality control in reloadingHelps identify concentricity issues that affect accuracyDurable construction for consistent measurementsThis professional-grade gaging tool is indispensable for competitive shooters and precision reloaders who need to ensure their ammunition meets the highest standards for accuracy and consistency.