[Hectic]

well just look at the difference between an mp5k and an ak with no upgrades the ak has far more effective range and much tighter groupings hands down, (i chose those two cause they use the same gear box and a simaler hop up unit) or look at a vsr vrs an m4 yes the hop up is deferent but other then that at th same fps or even less (ie a stoct tm vsr at 280 fps and an average m4 at 350+ fps only diff is a barrel 1.5 times longer)
also to note if u put a 460mm in a standard m4 with a 3/4 ported cylender u will be eceeding the volume of the cylender so it only will work to a point 3/4 can take up to 430mm i think. Ill try n find the link i use
in the end tho the difference is verry small and the best thing is if the barrel has a consisten smooth bore and that u have a consistant hop up unit and good air seal. Mostly the longer barrel ie the maximum or close to it that the cylender canhandle is just going to increase the efficiantcey of the gun allowing the bb to reach its maximum velocity as it exits the barrel with no wasted air from the cylender