[4V50 Gary]

I wouldn't worry too much about powder leaking from the barrel and through the flash hole into the pan. I read somewhere where some frontiersman tolerated it as it helped them to load when running.

The lack of spark is of greater concern. The frizzen may not be hardened enough and may need some kasenite to put more carbon onto its surface. You might also want to adjust your flint. I've used the same flint for over 130 shots (and it's worn badly but still sparks). A famous gunsmith confessed to me that he is cheap and does the same thing.

Test your frizzen by getting a fresh flint. Before you put the flint on, wet a piece of leather and wrap it around the flint. Wrap rubber bands around it to compress the leather and allow it to dry. When dry, clamp the leather wrapped frizzen into the gun such that there's good contact with the frizzen when the cock falls. Try that new leather wrapped frizzen to see if there's sparks. If you don't get sparks, then your frizzen needs the kasenite treatment.