The Sinclair Shoulder Bump Gauge Insert #17 is precision-engineered for accurate shoulder measurement of 30-06 Springfield cartridges with 17-degree shoulder angle.Sinclair Shoulder Bump Gauge Insert #17Designed specifically for 30-06 Springfield cartridges17-degree shoulder angle specificationPrecision measurement tool for reloadingCompatible with Sinclair shoulder bump gauge systemsEssential for reloaders seeking consistent cartridge dimensions and proper shoulder setback measurements for optimal chambering and accuracy.