IMO the difference between the 12 ga 3 1/2 and the 10 ga 3 1/2 is like the 20 ga 3 inch and the 12 ga 2 3/4. The larger ga shoots a slightly better pattern because the shot has a slightly bigger hole to come out of. This may not be true with all guns but with a majority of them. It boils down to how are your results and how well do you shoot the one you have. I have both and if I am going to be pass shooting or goose hunting I prefer the cleaner kills I get from my Browning gold 10.