Definately non ported length matters, particularly when dealing with low pressure. My Shocker taught me that. I started with its standard 14" AA, which used a messload of gas, requiring me to crank up my input pressure about to the 200 psi limit of the solenoids. I could only get about 800 shots off of a 114/3K tank. When I got my CP 14", it immediately lowered input pressure required to about 170 psi and I got at or over 1000 shots per tank. Number one issue was that it had over 8 non ported inches and not too much after that. Number two issue was that it was straight bore instead of stepped, meaning that gas was going directly towards pushing the ball down the barrel and not around it. I completely stopped using my AA barrel, traded it for a 9v conversion and some paint. To this day I don't know why they even make the stupid AA things anymore.
Such is the case with other guns, though not always to such a drastic extent. They still get lower input pressure and much more shots per tank fill, but such is more critical an issue with the Shocker, also noticeable with the BM2K. Currently I use BOA snakebite, Armson 2 piece, and S/M barrels on my Cocker, probably soon to get a Rekka.