John I kicked around the idea a while back in Over the Back Fence (where old posts expire) about a flow chart or family tree sort of organizing these schools of guns and some folks agreed that it'd be a great idea, but nobody sketched one out.
I think part of the difficulty is that experts tend to disagree on details, the other part is that it would have to be divided into time periods as well. Some experts might be best familiar with only one or two regions or time periods and not feel confident discussing nuances of others.
I know I've focused my attention on TN and neglected PA, VA, NC and the earliest guns. But I've learned some things about them all. The trickiest thing is that "Kentucky Rifles" doesn't just mean those made in Kentucky, but is the general term to cover most all guns of our interest. IOW Kentucky rifles were made in each state. It has to be utterly confusing for the novice.
And then there are the Ohio, NY, and SC made guns. Guns were made everywhere, but each location doesn't necessarily make a school.
I'll not get hung up on the term: School, Group, Type, Area or whatever anyone chooses to call a recognizable segment of the "American Longrifles". The term American Longrifles isn't perfect because many are smooth bores or fowlers. Choose your imperfect term and know that others may use different terms.
PA-made guns are often well known by county and even by the maker as well. Guns were made all over TN, but the most celebrated and archetypical are those of East TN, which varies somewhat, plus the Cumberland guns, which are a class unto themselves.
I yet think a few gentlemen/students/scholars of our early American guns could put together a family tree, perhaps in two or three time divisions that could roughly link together the development of the guns. There'd be a lot of footnotes and imperfections but that's just the nature of life. Problem is finding the funding or motivation for this to happen, and the folks who'd engage in the discourse/disagreements that would be part of the process. Perhaps some day*.
Until then, do look at the reference materials these folks suggest, make notes, and hang in there as you sketch out your own ideas of how it was.
*Would be an excellent American History project for student at university or graduate studies, if they yet do that sort of thing. The student could interview the most learned folks around, maybe get pics from grand collections, could let each person tell his version and then try to weave it into one balanced, historically accurate perspective. That'd take care of some legwork, but again, folks would fuss that this or that wasn't exactly right-could be fantastic project really.