Don't overlook George Shumway's work on Jaegers.
Get it, but you can disregard the regional attributions almost entirely.
Ok, some are right, but some are way off. Primarily in regards to guns with the star on the cheek (or other places). This is NOT a trait of guns from NW Germany. This is "Der Fraenkischer Stern", found on guns in the Main River area from Franken (or what the English insist on calling "Franconia") to Der Pfalz (the "Palatinate"), and a bit north and south of the river. Otherwise unmarked German guns with the star automatically get the designation "Sueddeutsch" (South German) in the German auction catalogs.
The North East has its own "school". Prussian (and surrounding area) guns are pretty readily recognizeable. The same can be said of Austrian guns in general. There is a very distinctive "school" from the Frankfurt-am-Main region, which shows through VERY strongly in guns from the Lehigh/Bucks county area. If you want to see a "Proto-Lehigh" gun, look at something from the Freund family of gunsmiths from Fuerstanau.
Otherwise, German guns can be VERY hard, if not impossible, to put a location on. Some basic forms saw widespread use, and gunsmiths did not necessarily feel tied to one particular form of stock. A gunsmith may make a straight-wristed gun one day, for example, and the next, make one with a stepped wrist.
You must go to
www.hermann-historica.com and check out their website. Buy some of their old auction catalogs...I have about 10 years worth. VERY helpful. Their later/current catalogs have much better photography.
For Swiss gunsmiths...you're on your own! I have had little luck finding any known Swiss rifles of the 18th century. I have no doubt that some of the "German" guns are from Switzerland, but who's to say. I have seen precious few photos of guns known to be from Switzerland. I'm sure that there are plenty, but I don't know where to go to see them!
Here's a photo of two of probably only about 3 Swiss guns I know of.
Note, by the way, the long barrel of the rifle.