As a side note I had one of the 338 guide guns and although I never chrono'd it I never doubted the performance of the 20 inch barrel vs a slightly longer one.
I actually killed my farthest deer with a 18 1/2 inch 7600 in '06 with 180 round nose bullets which would probably be the last rifle you would pick for hunting over a field.
Overthinking is a bad thing most of the time.
