Randy Nemetz said:
The problem I have is that every customer will want a Gauge R & R on their specific part. I feel this is unnecessary if I have an acceptable R & R study performed on another part.
GR&R and other MSA studies are a means of demonstrating not just to your customer, but to yourself that the measurement systems you've chosen are appropriate and accurate enough for the measurements required. Measurement system analysis takes into account any possible sources of variation, including not just the equipment, but the operator, staging, and the measured part and dimension as well. Simply because you have a GR&R study on one part that reports as being good does not mean that another measurement with the same equipment will have the same repeatability.
Taking a simple micrometer check for example, there can be differences in variation depending on the rigidity of the part, surface finish, available contact area for the measurement, draft in the area measured, etc. These differences from part to part can have a big effect on measurement variation.
Now consider measurements on a CMM. Sure the probing location will be more repeatable, but you still have other factors such as part flexibility, stable staging of the part, type of measurement, number of points probed per feature, etc. If you're using a manual CMM and not a computer controlled one, you can also throw out the repeatability of probing locations.
This is not to say that you can't take a GR&R from one measurement and use it for others, you had best be certain that the measurement method is similar enough that it will make little difference.