@MIG - The problem with the information calculated by mathematics is the fact you've negated the effect of air resistance - friction, and weather/variable conditions. the mathematical formulae will only apply if they are conducted within a frictionless environment, and I know you've stated it before. That said, the results from the mathematical equations will give a result far higher than what the real world would most likely see, resulting in what seems to be overkill in some eyes.

I know that a spherical shape will encounter approximately 3 times the velocity that it is travelling (not technically correct, but that's how I can describe it, ie increase velocity, increase the friction, therefore decrease acceleration), in terms of friction due to air 'particles', the darts, which for argument's sake will be a hemisphere - will encounter a similar resistance.

Also it would probably be better to quote initial muzzle velocities instead of average velocities, as you said, the speed of the dart decreases over time; as most blasters are like paper aeroplanes, their flight, dictated by the initial force behind the plane. The average velocity doesn't really give an accurate power indication of the blaster, neither would ranges (to the disappointment of many people, I'm sure). What would, would be either kinetic energy or the force exhibited by the blaster at a certain range. Although, the force rating would be a more realistic representation, over kinetic energy as force is the 'energy' transferred onto the player.

But then again, we are talking about toy blasters. Albeit, very interesting toy blasters...