Good point. I had always hoped that firing a couple of caps and then swabbing the barrel with an ISO alcohol soaked patch prior to loading would take care of any potential contamination, but I'm sure a certain amount of grease gets pushed up into the rifling ahead of the breech plug.

One thing that would be noteworthy to mention is that when wrapping teflon tape around the breech plug, don't let too much extend past the front of the plug. I can fold inward and block off the flash hole when the powder is added and bullet seated. Happened to me - once. Never had a misfire from the grease issue, though.