From what I have read, a 39 or 59 converted to DAO will have the long double action pull of the normal 39 or 59, but without the half-cock notch in the hammer. I have a DAO third gen 9mm (6946) and its trigger pull is much smoother, lighter, and a bit shorter than the double action pull on my 439. Based on that, I really would not want to convert my 439 to DAO. Just my opinion.