To be honest with you, the only 20 ga. I've ever owned has been a break open single barrel from New England Firearms. I got it when I was a boy. It holds a 3 inch shell and it is all I'ver ever used. I've never even "patterned" it. I've just used it, and I've taken my share of game with it, including turkeys. They've used 3 inch for a really long time and didn't need a 3.5 advantage until more recently.