I read Undaunted Courage maybe 10 years ago but I just don’t recall if it had any discussion on the air rifle - probably should reread it to see if there is anything substantial about it. Good book nevertheless. One obscure fact I seem to recall from the book was that each man ate daily something like 10 pounds of meat and now I wonder if they used the airgun with their hunting parties. When you think about all the calories they expended portaging their heavy boats and gear In unnavigable portions of the rivers, I am sure that they needed those 10 lbs of deer, elk, bison, etc to maintain their weight.