Lurch.....If I were you I would build a gun with one type of ignition....flint or percussion, personally I would make it a flintlock. You can find a touchhole liner and a drum that have the same threads and would be interchangeable, but, over
a period of time, if you change them very often, the threads will start to become worn and could cause trouble. If you
would build a new gun with a good fliint lock, which apparently you have not experienced yet, you would be amazed at
how well they work. You would also find that they are actually easier to maintain, and, you would remain in the good
graces of most of the guys on this forum......just joking............Don