Well as some put it "opinions vary". During my stint as a guest of the US Navy, one of my jobs was calibration. We Calibrated EVERYTHING on a submarine including all matter of pressure gages, torque wrenches , and calipers. Seeing first hand how much things were off sometimes, was to be honest shocking. Very good, high quality tools that would be out of spec. Trust what you can verify and results you can see for yourself. I am a firm believer in "if it ain't broke don't fix it. Hell my buddy Mike, who is a life long machinist, can feel a thou with his fingers. Yes, I have seen him do it and yes I have seen him take peoples money when they bet he could not. Todd