[Unclenick]

I've never noticed priming affecting length, though I suppose if you had a thin enough rim you could bend it back with the shell holder if you pushed on the primer enough. In any event, it's hard for a caliper to repeat to the nearest thousandth on cases. You rotate the case, wobble it into position and you can often get that much disagreement between successive measurements.

As I mentioned, you can feel a high primer with your finger. If you want a simple measuring test, place the tip of a flat blade screwdriver on the case so it bridges across the primer pocket. A narrow (narrower than the primer) strip of typing paper should be able to slide between the blade and the primer.