hmm, yah iv seen that bubble on KSCs before too, but i always just assumed it was a manufacturing defect/process side-effect. but i would like to see if i can get some hard numbers on this to see if it would be worth pursuing. ill ask some 4th year mech. engineers i know if they can do some finite element analysis on a 6mm hollow sphere, maybe in a few materials? and maybe even one in 8mm just for curiosity. i was also thinking (way outside the box mind you) that very thin walled brass (with low amount of zinc to decrease brittleness) sphere might work, as brass would be much denser than plastic so you could get as much of the effect as possible. that and most airsoft barrels are brass and brass-on-brass has self-lubricating properties if i remember correctly but might be wrong. brass is still a soft metal too, but i highly doubt that it would be practical simply for the reason that i wouldn't want to get shot with it, i don't think anyone else would either! and this is airsoft, remember? i think the only hobby with more lame/useless/hyped/expensive products/"accessories" is golf. but if the benefits are real and can be demonstrated... there will always be people out there willing to pay a premium.
the golf ball dimple idea is great! i don't know the exact science behind it, but i believe the basic principle is that the dimples cause the airflow to "ripple" around the sphere and decrease drag in the same way that a "boat-tail" does on a real bullet; by reducing the "wake" behind the ball. i wonder if sandblasting a bb (lightly) could have this effect? also there was a mythbusters a month ago where they tried to scale up the golf ball effect to a bowling ball, if someone can find it it might have some useful/practical insight into scaling it down as well.
gotta run now but this will be on the back burner today, keep the ideas coming guys