There are a lot of videos on fixing cap jam problems out there, many centered on the hammer face, and the way it cuts and/or grabs the caps off of the nipples.
One method prescribes filling in the safety notch on the face of the hammer which tends to grab the caps and pull them off the nipples. This has the unfortunate side effect of not being able to use the safety pins. Not the best solution and actually can have negative consequences beyond just rendering the safety pins unusable.
Another solution presented is to "break" the sharp edges of the hammer face with small files to prevent them from grabbing the cap. I have done this on my revolvers and it helps and find it works and is one valuable part of solving the cap jam problem.
Back pressure which lifts the hammer off the cap at the moment of detonation is also been proven to be a problem, blowing the cap off and under the hammer. Replacing the nipples that are worn or bored too large, with those with a smaller opening helps, as does making sure your mainspring is stout enough to keep the hammer down.
As the Duelist states in his video, this does not seem to be a historic, period problem, and is something related to the reproductions, and I agree with him that the less finished hammer face of the repros, and perhaps a weaker mainspring than the originals, as put forward by Eras Gone, are the culprits.