I’m no error expert just giving an opinion. The photo makes the groves look curved like an impression from a cylindrical object. Small bolt or machine screw.
My opinion is still the same four years later: struck through reeded edge fragment. The new photos illustrate how the surfaces are mint-struck on all areas of the coin, including the 'defective area'. It's smooth and lustrous like the rest of the coin. I would think that damage would be more ragged, with sharp edges, and disruptive to the luster.
That coin is not struck through a bolt, I believe it is struck through a fragment of reeding. I owned a coin which was struck through a bolt, the design next to the strike through would be much more distorted and not struck up nearly as well. Here is a link to a discussion thread on the coin I owned.
Sean Reynolds
Incomplete planchets wanted, especially Lincoln Cents & type coins.
"Keep in mind that most of what passes as numismatic information is no more than tested opinion at best, and marketing blather at worst. However, I try to choose my words carefully, since I know that you guys are always watching." - Joe O'Connor
That is not a strike through of a screw.... and not from the sealing machine...it could be detached reeding...too bad it was not retained. Much better pictures four years later.... Cheers, RickO
Can you pop it out of the Dansco and see if the reeds are normal and complete on your coin? It almost looks like a problem near ICA of AMERICA. Long shot, but part of the reeding die could have broke off and got stuck on reverse die.
Agree - can't be a struck through screw, there would be no contact between the die and planchet if a screw were there and not entirely embedded into the coin. Maybe struck through reeding as mentioned. If we did not first see it in the plastic (too bad it was removed) I would have guessed PMD at first.
Comments
What does the opposite side look like under the area in question
Opposite side looks ok, it would be between the 1 and the 9

Looks like the shank of a small bolt
My Ebay Store
So struck through a bolt? From the mint? Really? Wow can't be a lot of tbose around lol
Someone needed to suggest measuring the "teeth" and the "teeth" on the mint set packaging
Similar for the reeding.
I’m no error expert just giving an opinion. The photo makes the groves look curved like an impression from a cylindrical object. Small bolt or machine screw.
My Ebay Store
They sealed edge on a mint set was nowhere near tbe same pattern as this. Do you think this could fetch a premium?
Just when you think you seen it all............you always see one more.
Pete
My opinion is still the same four years later: struck through reeded edge fragment. The new photos illustrate how the surfaces are mint-struck on all areas of the coin, including the 'defective area'. It's smooth and lustrous like the rest of the coin. I would think that damage would be more ragged, with sharp edges, and disruptive to the luster.
To me it looks like a struck through spring. I would have kept it too.
Looks like a 1/4-20 bolt....i/4 " diameter 20 threads per inch.
That's my guess.
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That coin is not struck through a bolt, I believe it is struck through a fragment of reeding. I owned a coin which was struck through a bolt, the design next to the strike through would be much more distorted and not struck up nearly as well. Here is a link to a discussion thread on the coin I owned.
Sean Reynolds
"Keep in mind that most of what passes as numismatic information is no more than tested opinion at best, and marketing blather at worst. However, I try to choose my words carefully, since I know that you guys are always watching." - Joe O'Connor
That is not a strike through of a screw.... and not from the sealing machine...it could be detached reeding...too bad it was not retained. Much better pictures four years later.... Cheers, RickO
Can you pop it out of the Dansco and see if the reeds are normal and complete on your coin? It almost looks like a problem near ICA of AMERICA. Long shot, but part of the reeding die could have broke off and got stuck on reverse die.
I'm in the struck through reeding camp
Agree - can't be a struck through screw, there would be no contact between the die and planchet if a screw were there and not entirely embedded into the coin. Maybe struck through reeding as mentioned. If we did not first see it in the plastic (too bad it was removed) I would have guessed PMD at first.
The lines look......slightly.... angled to me.
Which would suggest a spring maybe. ?????