We won't know how repeatable it is until we build the last part, which is an arm that sits on top of the ball to hold it down, and is raised when we want to fire the ball. The idea is to use the downward force of this arm plus the weight of the ball to overcome the initial vertical upward force of the catapult...and then when the top arm is released, the vertical force of the catpult is greater than the weight of the ball, so the ball fires. In our initial tests using my arm as the ball holder downer, this seems to work ok, but we need to do some fabrication soon (ie today) to get that arm built and on the robot, so we can answer your question more accurately
