The bottom screw doesnt go into the opposite jaw of the vise, it presses on it. What you are seeing is the bottom screw wearing the black off, and then wearing the aluminum away. It uses pushing force to push the bottom away, so the top gets extreme leverage for clamping power.
I was thinking about machining a blind counterbore, and pressing a stainless steel insert into it someday.
Knives look good! great work!
