At 3 minutes in this video
https://youtu.be/tSZtt26PQug
So he is saying that the common test of being able to blow the paintball through the barrel is not good, right? Its better to underbore which would mean that you cant blow it through but you can push it through with your finger? So you want to go just tight enough so that the majority of the balls you cant blow through, but not any tighter then that right?