The hardness tester will only be accurate over the hardness range listed in the instructions. The indenter ball diameter determines the range over which the tester is accurate. We chose the ball diameter which would cover what we thought was the most useful range of hardness as it applies to cast bullet alloys.
Pure lead is beyond the range of our hardness tester. Pure lead has a hardness of 5 on the Brinnell scale, which would approximately be a .094 diameter indentation.
