Error ? Franklin Half Dollar

These are called "bag marks" from when coins clang with each other after the minting process. These are very common and degrades the coins. These can separate the high end MS coins.

A freshly minted coin commonly can sustain a 'bag mark' when it is ejected from the coining press and drops onto a heap of other coins. The coins dent and jingle together as they are gathered together in bulk, to be transported to the coin wrapping machines.

With more modern minting practices, coins are no longer wrapped, they are just sent out from the Mint in bags. At least, that is the current practice at the Royal Australian Mint in Canberrra.

The squiggle marks seen on the coins are where a coin with a grained edge has hit the face of another coin edge on. It it just not worth the Mint's bother to protect newly minted coins from this type of damage.

More to the point is to find a freshly minted modern coin without any damage on it at all. From my experience, such a coin found in circulation is indeed a rare thing.