I'm looking to get into a Beretta auto and REALLY like the look of the semi hump back 390. But I held a 391 in 20 ga. the other day and it felt like a racecar in my hands. By that I mean slim in the forearm and very light and quick to shoulder. I know both are great guns but how much wider/heavier is the 390? Are the stock dimesions (drop at heel and comb) fairly close to the same?