Roundball's advice to have the flint use a slight shaving angle is a truly important point to a flinter working well and fast. He wrote about it succinctly but thoroughly and it couldn't be more important. Many people don't understand that. It is a bit of a mystery even to some experienced percussion rifle shooters.
When I "came back" to doing Rev War re-enacting in the mid 90's (after having done it in the late 70's) I was very much surprised that many Rev War re-enactors had problems getting their muskets to fire with some sureity. Good heavens if any flintlock should work well, it should be a huge military lock with those extremely strong mainsprings, big flints and large steels (frizzens). After my first re-enactment as a member of the Major's Coy, of the Black Watch - some of even the more experienced members came up and told me they were surprised I didn't have any problems with my musket going off and how fast I could load and fire. (For my first couple of years with them, they kept forgetting I had done it almost 20 years before.)
One of the reasons was how poorly so many of the frizzens fit the pans. They didn't have the Japanese Besses when I first did Rev War reenacting and the early Itallian Besses we had and I still used, fit much better. When they put powder in the pan and "Cast About" as in the Drill Manual, much if not most of powder was slung out of the pan between the opening from the top of the pan and the bottom of the frizzen. I wound up refitting and re-hardening and annealing almost every frizzen in the unit. But, that didn't completely cure the problem. What I also didn't know at first was so many of even the experienced re-enactors didn't know how to choose a flint to get the lock to work like Roundball mentioned.
We had quite a few members who spent the extra money to buy some of the few original 18th century French Musket Flints that were still available. They thought buying original flints, which were made for muskets in the day, would take care of the problem. Instead, those flints were so long for most reproduction locks, that they hammered the frizzen and produced few if any sparks, like Roundball mentioned. They also had problems with flints breaking in the jaws of the cock and that was also caused by the flints being too long.
I know some people have good luck using the lead wraps for flints in musket locks, but for whatever reason they never worked well for me. Maybe it was I was used to using different thickness of leather to hold flints and I wet formed the leather for each lock. So what I did for our members was find the size leather wrap and flint that worked best for each lock. Instead of those huge original French Musket Flints, most of the Japanese Besses worked better with a thick leather wrap and a Track of the Wolf 7/8" or 1" flint, which surprised me a bit and took me a bit to figure out. Then I gave them some pieces of leather that fit their lock and wrote down and gave them EXACTLY which size of flint best fit their individual lock. After that, most of our guys got through a whole batttle reenactment without having to change the flints. Re-enactors fire a LOT more than they did in the original "live fire" battles and we sometimes got as many as 35 to 50 shots out of a flint after that, without knapping the flint in the lock or doing anything to the flint.
