I'm not so sure there's a piercing bonus on the head either, atleast not triple. I know for a fact that people in non-top tier armor have survived my overhead gen1 bec to the head with 11 PS. According to the dmg calc 33 str/11 PS/38 piercing to 40 armor does 53 average, if it was 3x then the total damage would be 159, which would be no way survivable. There does seem to be a damage bonus, because head hits with piercing are definitely more deadly, but 3x is too much I think.