The Sinclair Shoulder Bump Gauge Insert #23 is a precision reloading tool designed for accurate measurement of cartridge shoulder setback with a 23-degree angle specification.Sinclair Shoulder Bump Gauge Insert #2323-degree angle measurementCompatible with .223 Remington 22 Remington and 17 Remington cartridgesPrecision machined for accurate shoulder bump measurementsEssential tool for consistent cartridge reloadingPerfect for competitive shooters and precision reloaders who require consistent cartridge dimensions and proper shoulder setback measurements for optimal accuracy and safe reloading practices.