Phil,
You partially answered your own question. Other schools produced guns in a wide range of decoration, as you pointed out, from the barest "poor boy" type guns to elaborate guns with full patchboxes and silver inlay work. I omit carving as a decorative detail here since it was so rare in Kentucky. A few early rifles had relief carving... but it is impossible to tell if they were actually made in Kentucky, or made back east before the gunsmith moved to Kentucky. A few KY guns have incised carving, but that is also rare. So the primary, or most obvious, similarity of Barrens School rifles is their consistent lack of embellishments such as inlays and the basic butt and forestock molding lines found in most other schools.
Rifles in the northern end of the Barrens School retained architecture more related to finer central KY guns, while guns in the southern end of the Barrens School picked up influences from Tennessee gunmakers, primarily because northern Tennessee counties "donated" gunsmiths to southern KY counties during the area's early settlement days. Therefore, there are a few subtle differences in stock architecture in guns from the northern end vs. southern end. Also, on average, barrels were a little shorter on Barrens School guns than central KY guns, since as gunmaking went farther west in KY, barrel length became less of an artistic statement, i.e., longer barrels were more attractive, and more of a basic functionality [and cost] issue... of which decoration didn't play a major part.
A final comment on design consistency in Kentucky's two largest multiple-county schools, the Mountain Rifles of southeastern KY, and its southcentral Barrens School, is needed. Most gunmaking schools we think of, such as those of PA, MD, or VA, covered rather small, uniform areas. We can all recognize a York Co. gun, or a Berks Co. gun, or Lancaster Co. gun rather quickly, since the school was localized around a large city, or perhaps a single county. In states farther west like KY there were still easily recognized schools, such as the Lexington School or Bardstown School. Those schools were similar to the easily recognized eastern schools in that they centered around major towns, or perhaps a county. But as one moves farther west, population was sparser, towns smaller, and areas were less uniform in population make-up and artistic preferences. The end result in KY's larger schools like the Barrens School is more variation in its firearms, just as there was in its citizens. Yet to be able to study and understand firearms in those areas and how they relate to other areas in the state, assigning "schools" based on a larger area's common details is important, even if more variation is present than in smaller, more tightly knit gunsmithing schools. I hope that answers your very good question. And if you really want to learn about Kentucky gunmaking schools, its early gunsmiths, and how local styles evolved, the "Kentucky Gunmakers 1775-1900" books are still available at
www.kentuckygunmakers.com.
Shelby Gallien