Some glittering generalities about Tennessee Rifles based on my readings. Some of this has been mentioned by others.
The Tennessee area (and most southern states) had very few copper deposits but iron was rather common. Due to this, most of the southern guns used iron for the trigger guards, sideplates, toeplates, thimbles, nosecaps and buttplates.
As these parts were often hand forged, their designs were fairly simple. The trigger guards are often rather square looking and the rail was usually rather thin and close to the wrist ending in a forward facing or aft facing curl.
The comb of the buttstock is usually straight while the underside may be either straight or with a concave curve.
The stocks usually do not have the wide, flat butt plate which the older Pennsylvaia rifles have. The older Tennessee rifles have the medium width mildly curved shotgun style buttplates to the narrow, deeply hooked buttplates seen on the later mid 1800 guns.
Although many of these rifles have Walnut stocks, both plain and curly Maple stocks exist along with many other hard woods.
The rifles were made in both Flintlock and Caplock but most of the remaining original rifles are Caplocks.
The Tennessee rifles often have heavy barrels but the forestock is usually thin making the guns look light.
One of the unusual features found on the later guns was the long barrel tang. This sometimes extended the full length of the stocks wrist and has sometimes been found to extend up the front slope of the comb.
The trigger plate sometimes ran back along the underside of the wrist and the bolts between it and the barrel tang extended thru the wrist made a slender wrist without compromising strength.
Patchboxes were often omitted but this was not always the case. Either the elliptical shaped Capbox or a slender, long, iron patchbox with a pointed shape on each end (often called a banana style) was used.
Many of the guns which do not have patchboxes have a hole bored in the off side of the buttstock which many agree was used for patchgrease.
Inlays are rarely found but a few rifles have simple carving on the stock.
There are examples of rifles which have no buttplate, no toeplate, no ramrod entry thimble and no nosecap.
IMO, the scarcity of examples of all of the Southern rifles is due to many of them being destroyed by the North following the Civil War.
If I got any of this wrong, please feel free to correct me.