The guns that are commonly recognized as being "Lehigh" guns (curved) MAY have come into existence sometime in the 1780's. There is the "fully formed" Rupp gun dated 1793. They didn't just burst into existence, though, there seems to have been a somewhat gradual change going on, which may have speeded up dramatically at the end of the war. To see a good representative of a "Lehigh area" gun of the Revolutionary War period, one needs look no further than any of the Oerter rifles. These are from the early 1770's, and show a SLIGHT amount of curvature in the stocks...not much, though. Going back further into the 1760's you will see the famous "Christian's spring" type of guns. Some have straight wrists, most seem to have stepped wrists. The earlier you go, the more German the guns are. The German stepped wrist continued on through the later Lehigh guns. As far as "German influence", Lehigh guns have that in spades!