bgf,
I think that is a likely reason. But, I think that some of this is also that we don't actually fully understand yet what diversity and "individuality" Pennsylvania and other "northern" regions had to offer. Look at the work of John Newcomer or G.F. Fainot in Lancaster, or Deming in New England. I don't mean to rain on anyone's parade, but attributions are just that. They are not facts, but speculation. And speculation, no matter how well reasoned, is often incorrect. How many guns that we "know" today are Virginia, if a signed example or two by the same maker turn up, are going to be reassigned twenty years from now to Pennsylvania, South Carolina, or Connecticut for that matter? There were gunsmiths at work in Detroit during the Revolutionary war era. Anybody want to hazard a guess at what an 18th century Michigan rifle might have looked like? What about John Dodd's work in Charleston in the 1750's? Where did they place their pins? If we were staring one in the eye, would we even know it?
I think if we are going to be honest with ourselves in assigning regional characteristics, we have to stick to signed and located work, and not figure attributions in the mix. Eric already posted a Pennsylvania rifle with the long pin placement. I believe the Deming does have it too. How many other rifles that have the long placement that are documented as NOT being from Virginia are out there? If there is even one, don't we have to watch attributing unknown rifles as "southern" based on that characteristic? I have no doubt that the long pin placement is a Virginia characteristic, but I don't think it is by any means exclusive to the south.
(I have some of the current Deming information included in my talk at Landis this weekend if anyone is interested.)
Alan