The best way to improve the accuracy of your paintball gun is to "size the paint to your barrel". Every batch of paintballs will have a slightly different diameter. Because of this, you need to have a variety of bore sizes, the inserts accomplish this in an economical way.
GOG Paintball 16" Freak Carbon One Piece Barrel. The wait is finally over. Freak flexibility and bore-to-paint matching is now available with the amazing strength-to-weight ration of true carbon fiber. Not to be confused with budget built barrels that have a carbon fiber pattern printed on them, or a carbon rube wrapped in carbon fiber, The Carbon Fiber Freak is built of layered woven carbon fiber composite from its inner bore to its exterior for maximum strength. True All-American Porting dampens the marker's sound signature while providing a pathway for propellant gas to equalize with the atmosphere before the ball exits the barrel, with a unique size ration and patent spiral pattern that has been the choice of top competitive paintball players since the 1980's.