I agree with DELKAL. Years ago I used to rely on headspace gauges. That was long before the internet and easy access to SAMMI specs. I don't know if I ever had a German made 98 not fail a NO GO gauge. With the ease of accessing CIP(European) specs, things are a lot different now. It goes back to the 7.62 NATO vrs. the .308. Even the US military did not call it's headspace points from the same position as US commercial ammunition makers. It gets pretty complicated, but if every factor of tolerance is thrown in, it is possible to have one out of spec reading from one of the tolerances in the same chamber.