An exemplary bore for a shaft of a turbomachine includes a longitudinal axis extending generally from an inner end to an outer end of the bore, an outer seat disposed proximate to the outer end of the bore at an outer seat radius for an outer seal ring wherein the outer seat comprises an inner end, an outer end, a step at the inner end extending radially inward to a step radius, and a chamfer at the outer end extending radially inward over an outward axial distance to a chamfer plateau radius and an inner seat disposed inward the outer seat at an inner seat radius for an inner seal ring wherein the outer seat radius exceeds the inner seat radius. Various other exemplary devices, systems, methods, etc., are also disclosed.