FWIW, I think that a #2 pencil is comparable to an HB pencil. The trouble with using only a single pencil is that it won't tell you how hard the alloy is. It will only tell you if it's less or more than a single point. If a #2 cuts it, is the hardness B, or 2B or 6B? If you don't know what the actual hardness is, you can't reproduce it.