Hi George,
Perhaps I did not explain it well. My friend was not trying to find out whether his or the other fellow's equipment was properly calibrated. They would be having discussions that involved very small differences in bullet dimensions, perhaps involving some bullet that he did not have an example of in front of him , and he wanted to know that the net difference between what his equipment and technique and the other fellow's was. That is all. Of course you probably already knew that. The mention of using known standards to check measuring tools is entirely appropriate to this discussion. Before I had any standards (however coarse they might be compared to the best, that you undoubtedly have) I would compare measurements of the same thing, taken with all of my calipers and micrometers. Back in the day when I had my one and only machine shop class in college, the instructor, a fellow who had come from industry, gave us a pretty good rundown on measuring tools, which I consider myself lucky to have had.
The very first thing that he told us, before handing out the micrometers, was not to treat them like a C clamp, and why. I would say that he did that because experience had taught him what ignorant young men were likely to do.
Boyd
