The Benelli as well as the Beretta Xtrema have the rep in semi-auto's, though the new Remington Versamax will give them a run for their money. Waterfowl means two things, either ducks or geese. With geese, 3.5 12 gauges are really what you need. I have both a Benelli and Beretta, but with geese I tend to shoot an old pump Remington 870 with a 3.5 chamber the best. I just have a tendency to concentrate more on what I'm doing with a pump gun. The Benelli Nova, which I don't have is another excellent shotgun. With ducks I think you do just fine with 3 inch chambers.
