J&J elite barrel kit

[propaintballer2378]

Hi, I just recieved my J&J elite barrel kit. I am confused if I some how assembeled it rong. Because the barrel screws into the insert and the insert screwes into the gun. So the ball is the right fit at the beginning but when it hit's the barrel part won't it be loose again? shouldn't the insert be at the end of the muzzle so the ball will be tight fit when it leaves? please help.