ok dude in my limited experience of such things it reallu isn't a good idea to antagonise the guys on here.
ok so heres the lowdown on the paint/barrel thing.
paintballs are all 0.68 calibre. BUT different brands and batches of paint come out at different sizes. (normally between 0.675 and 0.698 ish (we are only talking about 0.02 inches here so it's not like your gonna be able to tell by looking at it or anything.). in order to get the best accuracy out of your paintgun the ball should not roll through the barrel or refuse to travel down it. instead it should take a gentle blow to get the paintball to go down the barrel. this is why most of the "pro;'s" have a selection of barrels or a freak system. so they can match the barrel they are using to the size of the paintb on the day (remember paint changes size due to temperature, humidity etc).
hope this answers your questions but i have to say if you get tetchy with these guys they will bite. they are giving you their time for free and i have to say that questions like "should i wear cologne on the paintball field (yes you did post this topic!) is only going to serve to irritate them and make them less likely to answer your posts in the future.
not meanng to get at ya mate but just a friendly word of advice.
enjoy your balling
elrikos
;-)
p.s. i have made way more than 3 posts (the tech guy is looking into it)