Its the heat from the burning prime that ignites the powder in the barrel, not bouncing or " leaping " sparks, Guys. If you use a pick to open a hole in the powder, thru your TH, the heat reaches more than one granule of powder, and ignition is accelerated a few milliseconds.
Its next to impossible to make general statements about guns made more than 200 years ago. There is no uniform sized TH, much less agreement on inside coning, or use of a TH liner that is coned, inside or outside. Most guns that old have had their bores " freshed" out- at least enough of them that you cannot reliably make a judgment at this late date about when or IF such work was done. THs in soft iron barrels were subject to more wear, and were often "cleaned up" by a gunsmith for a couple of pennies, by using a larger size drill to "square " the edges of the TH.
One of the reason that "judges " at rendezvous, and re-enactments don't disqualify modern replicas with Liners is that no one can agree on what was or was not done back in the day. If these minor issues disqualified shooters from participating, they would have no shooters! :shocked2: :redface:
These are good questions to ask, but no one should expect any definitive answers. No matter how old a gun is that is "recently discovered", and no matter how long "its been in the family", we just don't have reliable information on what was done to the gun after, or before, it reached the current line of ownership, over many generations. :hmm: :thumbsup: