Shortening a barrel does decrease range/power. The dart does not have as much time to accelerate before leaving the barrel and therefore leaves the barrel with less speed, in turn not travelling as far or hurting as much at comparable ranges.
Yes, if the only factor that changes is the barrel, ranges will suffer. However, if one also increases the pressure behind the dart, the dart will accelerate faster thus compensating for the shortened barrel velocity-wise. Of course there are disadvantages to doing so, like unstable darts, a louder muzzle report, and possible dart shredding.
Edited by Aimless, 17 November 2008 - 09:23 PM.