I recently got a 3'' Athena Loc Precisions Rocket Kit with a DMS H182R-14A Motor. I am trying to set up the motor tube but I am confused. The AFT is suppose to go on the motor tube but I am not sure what the use of it is for? I can not fit the motor tip through it either. I have another centering ring that I have to attach a shock cord. Can you explain to me what the AFT is for and where I should put the AFT and the shock cord ring on the inner tube so my motor can fit and I don't have complications. All of you will help! Thank you!