I've been shooting waterfowl now, for over thirty years and have arrived at a few of my own conclusions. One of them being that the 3 ½ inch magnum waterfowl load is a completely unnecessary American obsession.
The 3 ½ inch load punishes my shoulder, makes me flinch, causes my Browning Gold to jam, and does nothing that I cannot do with a standard 3 inch shell. Gene Hill said something to the effect that, if you can't reach what you are aiming for, find a way to get a little closer. I assure you, he was not suggesting the 3 ½ inch magnum as the answer!
I dare say, in the not too distant future, we may happily see ammunition manufacturers touting the "new" 2 ¾ inch waterfowl load that "does everything the three-inch shell can do...and more." I for one, certainly hope so. If we can land a spaceship on Mars, why can't we make a non-toxic waterfowl load in 2 ¾ inch that "knocks 'em dead" at fifty yards?
Now I will shock you by telling you I will not buy a waterfowl gun that is chambered to take anything less than 3 ½ inch magnum loads. I will not shoot 3 ½ inch loads of any kind, but I want a duck gun (and I think you should, too) that's made to handle the 3 ½ inch loads. Here's why.
I have been in duck blinds, duck boats, lay out boats, salt marsh ditches and a few other enjoyable places where three different gunners, all side by side, are shooting shotguns with three different length chambers. Ammunition is often freely shared and more than once, I have seen a 3 ½ inch chambered gunner hand one of his roman candles to a 3 inch chambered gunner - or worse! I tremble to say I have also sat beside a 3 inch chambered gunner and seen him load 3 ½ inch shells into his gun - and fire! I grabbed the next one out of his hand and asked him to read to me the engraved chamber length on his receiver. In all sincerity and innocence he said to me, "what's the receiver...?"
Until common sense and proper gun safety are back in vogue, my vote goes to the 3 ½ inch magnum duck gun, loaded with 3 inch waterfowl loads. And as soon as the ammo manufacturers roll out the new 2 ¾ inch non-toxic waterfowl loads, that can and do everything a 3 inch waterfowl load does, we will dine on roast mallard, teal and black duck with grace. Maybe even some geese. And yes, I will even let you give me the ol' sporting, college punch, right in the shoulder.