The laws of physics get us pretty damn far and are not based on an ideal world in any physics text past the 100 level. There is plenty that physical laws say, that airsofters forget when posting on internet sites.
All data is based on assumptions, and there are so many to be made in determining this kind of thing. Not every gearbox behaves the same, and even when you just swap barrels there is a chance that the seal to the air nossle is off enough to disrupt the data. And then who is to say, which is the ideal hopup, bucking, piston head, tight bore barrel, spring, nossle, bb etc...
The way to go about getting range data is to make constant as much as possible and take many data points and extrapolate from that experimental data the results you want based on various curve fitting equations and such. But without a large indoor range, high speed cameras, and many many guns and parts it will be hard to get really exact data, and data that will be of worth to the average airsofter. Not even taking into account the variables that someone trying to maximise their own gun will get right or wrong using our findings.