Interested in gaining knowledge of PA longrifles made by Wm. Schreckengost, Putneyville, PA I've seen many examples and would like to know if anyone knows how to tell which period they are from based on their style. I understand they are all percussion. Some reading indicates that square patchboxes preceded round ones as per Kaufman. Full stocks
preceded half. Are there other ways such as the lock maker to tell when they were made?