Got this off another forum, Hope this helps.
If there is anybody reading this who isn't happy with their accuracy and hasn't tried practice shooting with a wood "flint", it is well worth your time. Actually, I reckon that it's worth your time even if you're absolutely content with your accuracy.
About this time last year, I received a Lyman GPR .54" in flintlock. I've shot about 150 rounds through it but quickly developed a flinch when trying to develop a hunting load. A few shooting sessions shooting the same load didn't help. Using a light powder charge produced a slightly less pronounced flinch, but it was still alive and well. Even just aiming and firing from the pan didn't eliminate the problem. Deer season rolled around and I didn't trust myself enough to take my flintlock out.
So finally, I cut a piece of wood about the same size as a flint, and went to work firing the rifle completely dry. Why I didn't do this ages ago is well beyond me.
In short, it only took a couple of 15-minute sessions and my flinch has disappeared. My first session was interesting. The initial few trigger-pulls made it clear just how bad my flinch was. (I consistently pull to the left and slightly down.) Ten-or-so tries, and I was able to hold the sights on target and "follow-through". The rest of the session was just practice. A couple of days later, and I flinched again on my first try in my second session, but that was it. Not a single flinch in my third session.
I just finished my forth session and am about to go outside and try dry shooting with the pan primed. Here's hoping it goes well.
My impression of dry firing (no powder at all) is that its a convenient, cheap, and very quick way of getting in some practice time. One can do it inside and in only a couple of minutes can pull the trigger as many times as in a decent range session. It makes flinching obvious because, unlike firing actual loads, you can actually see what's going on. Best of all, there's no clean-up when you're finished.
I'm so glad that I finally tried this technique. It's a wonderful tool to have in one's pocket and an excellent complement to range shooting. From here on out, it will be hard not to have a dry firing session whenever I walk past my rifles.