Garry, I don't worry about it. First of all, I sand my tubes on a mandrel so my sanding lines are good and are at a 90 degree angle to hold better. For my students, I just cut pieces of wood on the bandsaw that fit in the tubes about a 1/4 of an inch and I show them to put a ring of glue around the end that will go in first and then three stripes from the front to the middle on each tube. Then when inserted into the blank, twist the tube to smear the glue around the tube completely. A little glue should come out the end (that way you know you have 100 per cent coverage inside) and I just swipe the end on an old paper towel. When you barrel trim with the correct barrel trimmer, the guide will help you clean out any glue. That is also why I have students glue one day and barrel trim the next, I know their glue is hard and will trim out of the inside if it is there.
God and family, the rest is icing on the cake.
I'm so far behind, I think I'm in first place.
Premier Bovine Scatologist
Host of the 2015 FAMILY WOODWORKING GATHERING