I have an auditor asking me if we do Cp/Cpk on gages for MSA. I've explained that we do Cg/Cgk for MSA but not Cp/Cpk, so I am getting a non-conformance. Has anyone ever heard of doing Cp/Cpk on a gage? I've checked the MSA manual, and it discusses relationships of observed process variation, and variance in the measuring system. It does not mentions Cp/Cpk on an actual gage. Am I off base or missing something here. I always thought that measurement system capability indices were Cg/Cgk. I'm lost on this one, and could really use some help. Any assistance would be greatly appreciated.