Yeah, I think that’s correct for Nicholson files.Some Nicholson I rescued. I had dipped it in HCL to clean the rust off and left the teeth in fairly grabby shape (I assumed some sharpening action). I suppose it's possible that it was a head fake and the teeth were mainly rust too. I think these anvil faces test in the 55-60 HRC range. I don't have hardness files, but I think most bastards are 65 or so?
that seems really high for a striking surface.
it will be interesting to see how they hold up