With a GBBR, using a longer barrel also increases your FPS lol
Remember AEG's and GBBR's are totally different animals. The same physics apply in much different ways.
And to sum up your friend, the typical noob response to range and accuracy is tighter, longer inner barrel and more FPS.
Whereas you can, in fact, get more range and accuracy gains from an $8 higher quality hop rubber and heavier BBs.