I know that PMD is a possibility. However, why would a coin counter cut a uniform shelf along the entire circumference of a nickel? If we are going with that theory, there seem to be a number of flaws—the precision, the uniformity, the symmetry on both sides, the lack of any other wear (on the 2000-P).
Wear, even from a machine, would leave a rounded edge, no?
I think my original guess remains a better working theory. The planchet didn't have a good rim. When the dies smashed into the planchet, they moved the displaced metal into a false edge. That's why the shelf is flat, because it's the original low rim. The cliff face appears relatively flat because the striking pressure falls off enormously where the die ends.
If we can identify a post-mint mechanical process that would produce this effect cleanly, uniformly, and precisely, then I think that would become the new leading theory.
Wear, even from a machine, would leave a rounded edge, no?
I think my original guess remains a better working theory. The planchet didn't have a good rim. When the dies smashed into the planchet, they moved the displaced metal into a false edge. That's why the shelf is flat, because it's the original low rim. The cliff face appears relatively flat because the striking pressure falls off enormously where the die ends.
If we can identify a post-mint mechanical process that would produce this effect cleanly, uniformly, and precisely, then I think that would become the new leading theory.