It is my understanding from reading various ballistic related articles in magazines and loading books that each inch of barrel length adds about 10 fps to the velocity of the load, hence longer barrels shooting harder. I can't say definitively, I don't own a chronograph.
As the owner of a 10 ga Rem 1894 with 32" barrels that there is a huge difference in swing characteristics between it and any of my single barrel guns or my Cirori that has 26" barrels.
So much so that I asked a local gunsmith to weld a 1" steel rod to an aftermarket screw on cap for my A5 with a 28" barrel. The A5 felt whippy and I wanted a more muzzle heavy feel. The rod started out about a foot long. Each Sunday I would take it to my local skeet range to shoot a round. Then I'd take it off and cut an inch off and try it again the next week. As I recall, I stopped at 9".
Wardens give the gun the evil eye when they check me....
Mergus