In practice you are still better off with shooting more projectiles even if the accuracy of each shell goes down. If it's worth the weight and reduced rate of fire however is something to keep in mind. One thing i dislike is that ammunition is tied to how many guns you have, I'd love to use two gun turrets on some designs but keep the added ammunition from a three gun design, even with the increased ammunition setting it won't always be enough for long range sniping