Interesting article, the only way to find these old flints is by sieving the dirt. There’s probably a lot of them out there but who could possibly find them.
Here’s a video I watched a long time ago. You’ll see that the French and English
flintknapping they talk about in the article is kind of off base.
In Brandon (England) where the video is based after they got as many blades off as possible the cores were used in masonry on the buildings. You can see the round shapes all over. This is proof that the English used the same technique as the French to make gun and cannon flints.
By the way if anyone wants truly superior flints contact Will Lord he’s still producing them.
https://youtu.be/qKDoy6j2lfk