Jim,
Instead of answering any questions, you only raise more. The first time I looked at a diagram of the internals of your liner, it was perfectly obvious to me that it was only a variation of Nock's Patent breech's internals. During that same time period a number of English gunmakers, including Nock, Manton, W. Greener, and others, had a great rivalry to improve ignition and even held public trials to prove whose gun shot best. However, only slight variations in the design existed, just as they do today among commonly available liners. This design is some type of modified bell curve. The design was carried over into English percussion guns which rapidly overtook flint designs during the same time period, and rendered them obsolete.
Actually, someone did take apart some original guns to inspect the touch holes. Lynton McKenzie had a number of original English guns that he shot. He noticed that some of those guns were much faster than the others.
This information is probably lost since Lynton has passed, but raises questions. I'm sure all his guns were by well known makers, but we know that the liner is only a small part of lock time and that other factors of the gun's design also contribute to speed. I believe that your original Manton lock was the fastest as tested by Pletch. He has also shown that speed is subjective since only milliseconds exist among his tests and that although some speed variation exists among different liners, this variation is not discernable, because it is only one part of the equation.
What bothers me is that the commonality of all these English guns is that they had patent breechs. By their design, the internal cone is drilled from the off side of the breech and the resulting hole filled with a plug, usually platinum. Once sealed, it is impossible to see the internal cone unless the plug is drilled out. Are you saying that Lynton actually did this, which seems illogical to me, or that the guns he examined did not possess patent breeches but only had regular plugs with internally coned holes? Given the development of the English gun at the time, this also seems illogical to me. Are you saying that the guns he examined did not have patent breeches?
Upon inspection, he discovered that the ones that were fast has a specific shape of internal cone. He gave a talk about his discovery on the back poarch of Gun Maker's Hall at Friendship one shoot. Bob Harn and Mark Silver tried making liners to the specifications Lynton gave in his talk and found that those liners seemed to really speed up ignition.
Given such an august body of historically correct builders, I wonder why they did not pursue the replication of the internally coned touch hole instead of taking the easy way out and just making a liner. This only reinforces my earlier postings about coned liners being a 20th century adaptation of earlier technology. And the question still stands, "How did 18th and 19th century American builders handle this situation?" Who has disassembled a sufficient sample of American guns to provide a statistical sampling to deduce whether internally coned touch holes or straight drilled holes were the "norm." Other than the few anecdotal examples others have given, I don't believe this has yet happened.
