[Kelvin Ng]

Although this is a bit off topic, remember: when a component of the turret's aim angle is perpendicular to its velocity, the ball trajectory is going to be off a bit. A barrel will exert a force (depending on barrel length) upon the ball sideways, veering the ball off course. In addition, the component of the robot chassis's velocity perpendicular to the ball launcher's aim will also exert a force on the ball in the sideways direction. This might have to be accounted for by programming? Perhaps a shorter barrel would be a better idea, keeping you within your size restrictions. A turret is meant to be able to shoot while the robot is moving from any direction, so a long barrel may make it less accurate.