Yeah, inner barrels are great. Cough cough, Redwold order! Even swapping down to a 6.04 will warrant 15%-25% increase groupings and a jump in FPS. The problem is when you start getting down to 6.01 you need to pay for the TOP of the line BB's. We are talking about the competition BB's.
Maruzen Super Grand Master 0.29g 500rnd = $30 from ASA
These are more expensive than paintballs. Ouch!
-Doug