Does anybody discount that 18th century muskets and trade guns had straight drilled touch holes?
Straight drilled touchholes on common muskets of the 18th century were considered "OK" in a situation where misfires could be quite detrimental.
Until someone shows us some original Kentucky rifles without evidence of being reworked, having touch hole liners, or internal coning, it is appropriate to assume they did not. Any other hypothesis is wishful thinking. People get mixed up between what they want to believe and what there is evidence for. There's no logic to "you can't prove they didn't".
This does not mean all the white lightning lovers need to get defensive or ticked off. Just say, "I like 'em, they work, customers like 'em too; that's why I use them."
The NMLRA was born of competitive shooting and most of today's longrifles reflect a blend of desire for maximal accurate performance and historical accuracy. It's OK.
The trade guns were not considered to be particularly effective and the various European Gov'ts surely did not want the natives armed with anything that was superior to what their military used. Though the trade gun was about a toss up.
The Musket was pointed like a shotgun by most of the rank and file. I suspect the reason that they shot a few volleys then charged was due to the muskets becoming unloadable in a few shots with paper cartridges and the typical 18th c powder. So the vent was not terribly important and could be 1/8". There are numerous photos of self priming British shotguns with large vents in the Gold or Platinum liners. Accuracy is not important in a SB.
Other that having the some of the same parts there is little in common between a rifle and a musket. The trade gun was designed to be a throw away when it got to rusty or worn or broken.
Part of the wiping process often mentioned in the 18 c rifle loading process may have included the vent. Boone used a feather when shooting squirrels with Audubon.
I use the flintlocks I have as hunting arms. There is little more frustrating that working an hour or so on a stalk and having the gun flash. I have had this happen twice that I recall with a clean gun but never with one of my design liners or a Chambers. Some liners may be no better, if as good, as plain vent.
I would be interesting to see if there was a reliability difference in straight drilled holes of different sizes and a liner like a WL.
I put in a liner (similar to WL) in a barrel and left the vent .040". I shot the rifle 10 shots with no regard to the vent what-so-ever and it did not flash until shot 9. Had I CLEANED around the vent I doubt it would have failed then.
So I use liners. I like flintlocks. I use them for serious purposes. So reliability is important. There are American made arms with English style liners. Thinking these were unknown in America is unrealistic. Thinking they were adopted en mass by makers in the areas away from the eastern seaboard population centers, or even there, is not realistic either.
Some today are so hung up on appearances that they are apparently unable to even hunt unless dressed "historically correct" for their "persona". I don't have this problem. I will not be seen with a blaze orange weskit. I like FLs. I like hunting with them. The intrinsic value is in the lines, the art and the mechanism. The vent is just a flash hole that has to do its job reliably. I does not change the lines or the art. It does improve function. I consider it a good trade off for having a shiny place on the barrel next to the pan.
Dan