I have only talked to one person who claimed to have a 40 Newton altho when I pressed him about it, the facts he supplied did not seem to support the rifle as being original. I was able to purchase a 1922 Fred Adolph rifle in .40 Newton. It would have been made just after the time Newton put out his chamber dimention chart for his calibers in 1919. The chart lists the 40 with a .408 bore and this rifle has that bore size along with the other chamber dimentions listed in Newton's chart.
Larry

LSW