nysbowhunter - the person you want to ask is Roundball. I am not new to muzzleloading or flintlocks for that matter. I've owned and shot them for years. My problem was the art of Knapping a flint. It eluded me every time I tried.
Roundball explained it very well to me. Another poster, Russell sent me pictures of his knapping tools which I reproduced in my shop, and I can honestly say, I finally knapped a flint. After doing it, I wondered why it took me so long to learn.
As I understand it. I leave the rifle in half cock with the flint in the jaws. I then take the nail tool and lay the upside down L part of the end just barely on the edge of the flint. The object is not to knock off large chunks but just to chip the very edge sharp again, as Roundball explained.
I then work the edge end to end, and am amazed at how very sharp the flint is again. So far I am about six for six with knapping flints now. I've shot the flintlocks two days in a row and all the time have been able to put a new edge on the flint.
Many people do turn the flint upside down about every ten shots and let the flint and frizzen kind of re-knapp itself.
I am sure roundball will see this post and offer some much better advise then I can. After all I just learned how a couple days ago. Now I get to go back and try and re-knapp all those old flints I have been saving. Good luck to you.