The Sinclair Shoulder Bump Gage Insert #21 is precision-engineered for measuring 21-degree shoulder angles specifically for 220 Swift cartridges.Sinclair Shoulder Bump Gage Insert #21Designed for 21-degree shoulder angle measurementCompatible with 220 Swift cartridge casesPrecision machined for accurate reloading measurementsEssential tool for case preparation and sizingPerfect for precision reloaders who need accurate shoulder bump measurements to ensure proper cartridge headspace and consistent ammunition performance.