Isn't what you get based on contact of the "pack" material with the action bar/sideplates? If so, variability can't be entirely owing to intention and perfect technique, can it? I haven't seen that negative imprint of a "bunch of grapes" before. Pretty neat in my opinion. The same light tan "fisheyes" are on the Fox pin gun also. What would cause that? Pack breaking away from the surface before it hits the quench? I don't think Dewey is going to go in for torching and none of the examples look like the spread of temper colors.
jack