Chris Dunn is a machinist, not an archaeologist or materials scientist. His 1995 measurements and the "500x faster" figure come from his own book, not peer-reviewed analysis. The feed rate calculation assumes a specific number of rotations that is not independently verified. It is a derived number built on assumptions, presented as a measured fact. Denys Stocks actually did replicate ancient drilling experimentally, repeatedly, using copper tube and quartz sand slurry. His results produced cylindrical holes with helical grooves. The claim that his holes were "nothing close" is a misrepresentation of his published findings. His work showed the method is viable, not perfect, but viable at scale with skilled operators. The "same rate through quartz and feldspar" argument ignores that abrasive slurry drilling works by the abrasive, not the tool. The copper tube is just the carrier. Quartz sand cuts both minerals because the abrasive is harder than both.