1823 Bust Dime. PMD, Counter Stamp Or Something Else?

Exactly , like a really deep back mark you might see on a Morgan.

I agree. Some sort of contact, so PMD.

I agree with PMD - almost looks like a single row of vise marks.

Those are not PMD, those are dentil tracks. I personally have not seen them on a dime (not my series) but they are scarce on Capped Bust half dollars which I heavily study. Here is what they look like on bust halves:





Dentil tracks are a sign that a coin was double struck, with the first strike off center. Because of metal expansion and warping on the Z axis when a planchet is struck off center, the dentils are the deepest part of the design and are the last to be struck out. Hence why they are only visible on one side without evidence of other design detail. I believe this may be evidence that the reverse die was used as the hammer die for this die marriage as well.

NGC would likely ignore it altogether on a regular tier, but you should certainly attempt to get "mint error double struck" on the label!

Ah! Fascinating. Thank you for sharing.