Yes, I am saying you don't want the TH covered by the powder in the pan, if you want fast ignition.
An off-set TH in a new liner would do the trick.
My buddy, Don, when he converted my rifle from percussion to flint, found that the hole in the barrel was not centered properly to allow a proper position of the TH. So, he put a steel plug in the existing hole, welded it in place, filed it to the barrel flat, and then drilled a new hole. He put the White Lightning liner in the barrel.
Now, at the time, everyone was saying to use a " sunset" position for the TH- that is, half above and half below the line draw across the top of the flash pan. That is what he did. I later found that the gun would misfire, and I had to open up the hole in the liner, finally to 5/64" to get reliable ignition.
My fowler, built in 2004, by Craig Witte, of Fairmount, Illinois, has that TH located .030" ABOVE the line across the pan. He instructed me to fill the pan completely with priming powder, to insure reliable ignition. I have followed his advice, and the gun goes off fast every time. I do use a vent pick to poke a hole into the powder charge before priming the pan. That allows the heat from the prime to enter the barrel and ignite several granules of powder all at the same time, setting off a quick series of several " fuses" to get all the powder charge burning as fast as is possible in this open style of firearm.
By comparison, a friend who owned a Cannon we built tried using commercial fuse cord to light the cannon, and then poured both 4Fg and 3Fg powder down the TH in the top of the cannon to see if we could get reliably FAST enough ignition that we could time better the actual firing of his cannon.
The fuse was hopeless. You never knew when the gun was going to fire, no matter how consistent the length of fuse was cut. We tried both the fine powders down the TH, and as long as he blew the ashes off the end of his rope " MATCH", ignition of the main charge came within 1/2 second of when he touched the ember to the prime.
This was important, as we were asked to provide some comic relief to a model airplane show. The club had built an " outhouse" with sides that would fall down when strings were released inside. One of the members was dressed as a clown, and would enter the outhouse. We had the cannon in a small ravine behind the outhouse, where the audience could not see us. The people flying a replica of a WWII bomber, had a small plastic " bomb " that could be released by remote control. When they targeted the outhouse, the clown was inside, and we were able to time the firing of the cannon towards the outhouse with a load of mostly flour with the dropping of the " bomb", and the collapse of the wall,so that the clown appeared from the cloud of smoke, with what appeared to be his pants down, and on fire! The audience loved it, and, frankly, it was a very interesting problem to solve using a replica British Light 6-pound field piece. The club members were Thrilled that we helped them make a success of their " show". And everyone- including the club members-- gathered around to ask questions about his cannon.
