Wow, pistol schools, that would really be dicey. There are those who like to subdivide and slice and dice schools. Some even get their jollies by creating new ones. There is an urge in homo sapiens to scratch our story on the cave wall. Sometimes that's progress, at other times intellectual masturbation.
My initial reaction is that there are not enough extant pistols (that are real) out there to put them into distinct regional categories and have patterns pop out definitively. I would be suspicious of anyone, other than the Great Pinyone, who would offer to identify a Berks pistol from a Lancaster-made one. Now if someone told me that North Carolina pistols have some characteristics that regularly differ from Pa.-made ones, I want to hear everything this chap has to say. Then I am going to apply those notions to reality and see if my own empirical observations correlate to his.
I build what I call a Pennsylvania pistol. I call it that when I peddle it. It is a synthesis of the handguns in Sam Dyke's first pamphlet on local pistols. No secrets. I start with one of Fred's standard pistol forms and have him inlet the barrel. I go from there and never make two alike. They sell faster for me than rifles, because all the professional builders focus on the more expensive rifles and don't want to be bothered with these humble things which have so little space for carving expression. JWHeckert