That's an interesting piece Bruce. It's almost archaic now and as you say, just SOO subjective too. We used an old IZOD tester to test the body locking lug and bolt lug hardness at the big Base workshops. It was a ball impact at a certain load. Certainly no Brinnell or DPN. When they were doing the trials to test the suitability of a longer bolt head, they used a similar testing method. But as I mentioned, it was soon established that if a rifle had run out of CHS on a No3 calibrated bolthead in the gauge, inspectors, bolt, then the hardness had broken through or down