Since retiring I have been looking for a gun related business. Recently I purchased an ultrasonic cleaner and wow what a difference that cleaning made to all of my guns. My question, do you need a FFL to do gun cleaning? My idea is to have them mailed in cleaned and returned by mail. I really can't find any information about it other than reading threads that say if the gun stays on site overnight you must have a FFL. Does anyone have the answer?