The Sinclair Shoulder Bump Gauge Insert #35 is precision-engineered for measuring shoulder setback on cartridges with 35-degree shoulder angles including 30 Nosler 284 and WSM cases.Sinclair Shoulder Bump Gauge Insert #3535-degree shoulder angle measurementCompatible with 30 Nosler cartridgesWorks with 284 Winchester casesFits WSM (Winchester Short Magnum) casesPrecision reloading measurement toolEssential for precision reloaders who need accurate shoulder bump measurements to ensure proper cartridge headspace and consistent chambering in rifles using these popular cartridge cases.