Back in the mid-70s, the Warrenton Gun Shop in Warrenton Va, near where I was stationed at the time, was selling original flints from Harper's Ferry that were identical to the one in the picture. I think they cost $1.50 each, but can't really remember. I only bought one--could kick myself for not buying more-- and used it up completely in my Navy Arms Charleville musket (could kick myself again).
As other posters have already said, who knows for sure about that particular flint? Very interesting find...
As an aside, about 15 years ago, I bought an original cannon flint from the shop at Museum of the Fur Trade; about 2" square, for $5. Again, shoulda bought more.
