breaks are a day ruined for me, it gets everywhere and i go OCD mad just to get the inside as clean and smooth as possible.
If you want to increase your accuracy yes the paint will have an influence on this but the best way to combat it is with bored barrel kits, such as the smart parts freak kit. This kit can change the insert of the barrel to match the size of the paint (as the paint swells in size due to atmosphere) so it can be snug or loose on the inside of your barrel. This can also have an effect on your velocity but ill get to that in abit.
So if you can have a bore size of the barrel to match the diameter of the paint on the day then you will shoot straighter, best way to compare is like a modern day gun or even tank barrel. These are bored and have cuts/lines on the inside to ensure the shell goes as straight and as far as it possibly can.
Now i mentioned this will also increase your velocity. It will when you insert the correct bore size that day as you want the ball snug in the barrel so as its struck by the bolt it is propelled through the barrel with minimal friction from the sides but at the same time not soo loose that it can move around and effectively bounce in the barrel so when it comes out it swirls in the air. Smart parts have a great video advertising their freak kits and if i had the money i would of invested in one, but at the time i opted for a carbon tank. Now i like the freak kit as its all in one, but there are others such as the dye boom stick so go to any paintball site and go into there barrel sections.