All other things being equal, yes. It simply adds more weight to the gun.
This is most noticible in my Super Blackhawks, one with a 5" barrel, the other a 7 1/2" barrel. The shorter has more "whip."
As to difference in velocity, I've chronographed some .357 Magnum loads that are considerable higher out of my 4" Model 586 that out of the 6" gun. This with Hercules (now Alliant) #2400 powder.