my current marker setup is:
12v viewloader w/x board
i found farily large to medium size paintballs to be the best for me. a local shop owner recommended pmi paintballs.
flew very straight and accurate
didn't like small paint i guess
as long as i used fairly large to medium paint the barrel worked just fine. i was able to do the one shot/kills that are so hard to come by. only time i ever had a problem was when i was using the diablo dusk paint and sometimes the paint didn't fly quite as straight, once again i think that the paint was too small for the barrel. I put diablo dusk paint in my new e-pipe and found it fit best on .683 a little bit too small for the warped .689, with this awsome barrel i would suggest something like pmi superswirl or marbalizer, either one should work fine. My friends and I tested the barrel on a shutter, gt v1, sonix, e-99, and a black dragun. It worked as awsome on all of them.
great barrel, i would definetly get another one if i needed it. fairly cheap, i payed only about 50$ at the store in my town. as long as you use medium to large paint it will treat you just fine and give you some amazingly accurate shots with nearly any marker. i give it a nine since the bore size is so large and the trying to find the paint can be a pain sometime trying to get it fit for this barrel, still the accuracy makes up for it.