You can knapp the flint using the frizzen this way:
With the pan empty as well as the barre, for safety, raise the frizzen UP using the inside flesh next to your thumb nail of your fore hand, while holding the hammer( **** back with your strong hand' thumb. when the frizzen is raise enough to allow the edge of the flint to hit the HEEL of the frizzen, STOP.
Now, **** the **** back to full-****. Make sure that your weak thumb is back enough that it won't be cut by the flint.
Holding the frizzen in this slightly raise osition, simply pull the triger to release the hammer. The edge of the flint strikes the heel at a very steep angle, and with enough force to knapp a shard off across the entire width of the frizzen. The Spawl comes off the bottom side of the edge., creating a new, sharp-angled edge that will give you many more shots before becoming dull.
The only thing to do next, is to set the hammer at 1/2-****, then close the frizzen, and look to see how much of a set-back gap there is between your new edge, and the face of the frizzen. If its too much, you will need to move the flint forward in the jaws, bracing the flint and flint rap with some kind of solid wedge--twigs are God's wedges if you don't keep such things in your pouch.
With the repositioned flint, you are ready to shoot again.
I have done this marching in a parade where I could not step out of line to use some kind of table or rest to hold my gun and gear to knapp my flint any other way. It works. :hmm: