That can happen when you first start using the CCW turn, but if you tighten the joints with pliers or such it does help a lot. The CCW turn brings every thing or most everything back to the breech without pushing a bunch out into the barrel...'
To tell the rest of the story....
My first step to cleaning the barrel threads is to use a an old TC breech bore brush or one I have fashioned onto a stick to reach in and remove the excess tape that still might be in the BP port. Also turning CCW - then I can easily pick put the excess Teflon from these brushes and keep the actual hard working bore brush fairly clean,
Then after the breech is cleaned with similar devices - I will then use the drill/brush combo to really clean the threads and the BP stop in the barrel. Both will have clean bright surfaces.