There seems to be quite a few airsofters out there who seem to have the illusion that, the longer the inner barrel, the more accurate the gun. When asked for reasoning, they explain that the longer an object travels in one direction, the more likely it is to remain going in that direction. Let me tell you now that there is NO real scientific basis for this ridiculous claim. The other thing they point to is that field airsofters use longer guns, like M16's and snipers. This is because a longer inner barrel allows for more acceleration of the BB prior to leaving the barrel, and thus yields a higher velocity. In other words, longer barrel = potential for higher FPS, which also = potential for being accurate at range (because obviously a BB needs to be 200 feet away for it to be accurate 200 feet away).
Once a BB is traveling in a direction, it is going to remain going in that direction unless acted upon by outside forces. The forces that will ultimately be fucking with your accuracy are those imparted by gravity and impacting air particles (what most people would just call "wind"). If variables that affect consistency are kept as constant as is possible within the gun (mostly the hop up and the smoothness of the inner barrel) then the BB's inertia is going to be the deciding factor in accuracy (assuming FPS is a constant). Because a BB's inertia is directly proportional to its mass, the BB's mass is going to be the most important thing for consistency (which IS essentially accuracy if you know how to adjust sights). However, this is dependent of controlling variables within the gun, so inner barrel quality (not length) and hop up quality are also going to be very important.
So please, no more ridiculous claims that a longer inner barrel make for a more accurate gun. Oh and all you people that are hiding longer inner barrels in silencers are really wasting your money!