[volteco]

Originally Posted by Rossco66

You essentially are just taking off the sharp leading edge to avoid any binding with the BB hitting the side of the patch as it comes through the barrel. I personally don't get too fussed about the outside sanding after everything has cured. I mean its airsoft and there are a number of different inner diameters on barrels as well the fact that BB's vary in size from one to the next. Less so for higher quality BB's.

My point is, don't sweat it if your patch and the outside of your barrel aren't precisely the same. A very slight difference in my experience doesn't amount to any difference at all. I'm sure that on some level getting it perfect must provide some benefit but I haven't seen it. This process requires some patience and some common sense. If you don't have either, get someone to do the job for you. The HS5 kits are great but if you are planning on doing a few, then buying the tubing from McMaster-Carr is far more economical. Of course, then you have to cut your own patches which is another story altogether.

Good luck, the modification yields phenomenal results when performed correctly.

Do you know what tubing it is on Mc Master Carr by any chance?