Quote:
I though it was a strike thru
When a coin is struck through an object, the cavity is generally flush to the coin surface. The force of the hard steel die pressing into the planchet surface prevents metal from being raised. Generally, raised metal next to the indentation indicates a ding from post-mint damage. Raised metal without an indentation or scrape could be a die chip or gouge.
Lack of raised metal is for small strike-through errors. Large errors can have all sorts of appearances because the coin surface is so deformed.

Proof nickel struck through a thread.