There are just too many variables and he didnt incorporate some of the most important ones in his equations. The equations are very sound if a paintball had an equal distribution of mass thoughout its body (has the same density) but thats just not the way it is. For instance, if you spun an egg versus an object made of wood the same weight and size of the egg, they would have different spin characteristrics. In the end there are just way too many variables to deal with when it comes to calcualting how a paintball will fly. He also forgot to include air friction, and a number of other things. Comparing closed bolt and open bolt designs and how they would effect a paintball would take years of research in a physics lab alone. So I personally think this a gross over simplification.