Put up or shut up? Maybe, just asking the questions would be a better way to proceed. I have nothing to hide, scores to settle or anything to gain by doing what I do. I'm not a collector or fan of any brand, but I have noticed some trends among them, good and bad. Most people seem to like what I do. The only negative responses come when someone doesn't like the results.
Reading through the 4 short paragraphs you left, I deciphered 3 questions. You would like to know what the difference is with one point on the Rockwell C scale, and more about how it works. There are literally hundreds of pages that can explain it way more than I can. Google is your friend here. What I will tell you is that it is not linear. the difference between 60-61 is far greater than 30-31.
The second question seems to be about the machines themselves, and their accuracy. I'll limit my answers to C scale only and the Wilson I use. UCI, other portable testers and Superficial testers do not work the same and have different limits of error. Most quality manufacturers have a +1/-1 limit of error. What that means is if the machine they produce tests within +1/-1 point within the required test conditions, it is acceptable to them. Consider it a kind of tolerance, like the HRC range given by knife makers. Now this is where most people make the mistake of thinking every machine has that limit of error. That is the maximum limit of error acceptable, not the designed target. Good quality machines, that are maintained and calibrated regularly, can be much more accurate than that. Which leads us to the third question, or group of questions.
The third question seems to be about where I work, what we do, and if the equipment is good enough to give reliable results. I will not disclose the company I work for. I work for a company that is a design and fabrication shop. It's a machine shop with a big engineering department! We make high pressure equipment primarily for the oil, gas and chemical fields, but quite a few others as well. We use about 120 different materials from A286 to Zirconium. Our products are used in applications that require up to 150,000 psi, often volatile substances. We are a DoD/NASA contractor, and have been for many decades. As for the equipment I use for testing, the PMI gun is
https://www.thermofisher.com/order/catalog/product/XL3TGOLDDPLUS. The Rockwell tester is a Wilson 4JR. It is ancient! The machine is probably older than I am! That said, it is the most accurate tester we have. That's why they keep it and use it daily. We have a fairly new Instron Digital and Phase II UCI testers, but that old Wilson smokes them both when it comes to accuracy and repeat-ability. It is calibrated every 60 days, and serviced once a year or when needed. We use Wilson standards discs before and after, and sometimes during testing. Repeat-ability is under .5 consistently. When testing knives, I do one reading, unless the owner allows me to do more. I give actual readings with decimal, I don't round up or down. Our ISO procedure is written that way for single readings or single parts with multiple readings, so that's what I do. When I am permitted to do multiple readings, I have found very little variance on steels with a good HT. Usually, a half point or less. Steels with a questionable HT can show a huge range. At this point, I have tested somewhere between 250-300 knives. I have had my results backed up by a few companies that have had the blades retested by outside labs that have confirmed my results. There was one small company that had some issues with their equipment. They sent test blocks that I gave them to a Swiss lab that verified my results. Because of that, they shut production down for a week, bought a new tester, new heat controls and redid their HT protocols. Another has sent multiple samples to see if their issues had been fixed. Two others replaced blades, somewhat begrudgingly, from what I was told. The testing isn't perfect, but it is way more accurate that someone using a knife for a bit and guessing.
Anything else? Just ask.