There is a metered pulse of co2 into the propellant chamber of the gun when the trigger is pulled, and it's effect is gone at the end of the short barrel, and the longer barrel friction just degrades ball speed, so you get more drop to target, and have to figure barrel elevation into your firing solution. In general, accuracy will suffer, as it's harder for a shooter at a given level of skill to integrate another large factor into what's almost always a snap shot, aimed by end stink...

Not responsible for advice not taken...