Noticed your problem with fouling at the vent and your use of Bore Butter. Have never used Bore Butter, But have used a host of other lubes, many of which were home brews. Had fouling issues with all of them. Had to clean between shots and therein lies the problem. When you clean between shots you push the fowling down into the breech area, and when you reload, the fowling is between the vent and the powder charge. I switched to the use of spit patch in all my flinters many years ago, and have never looked back. I can shoot all day long without cleaning between shots and, at the end of the day, have little fouling to deal with. Hre's the process and why it works. Put the powder charge in the barrel. Pop a dry patch in your mouth and get it good and wet while retrieving a ball. Seat the patched ball in the normal way. It works for two reasons. First, the wet patch softens the fouling in the barrel. Second, the patched ball pushes the fouling down on top of the powder charge and it is expelled with the shot. There are those who claim the process is unsafe due to the possibility of a spark igniting the powder charge. In more than twenty five years of loading that way, I have never had an incident and have never heard a first or second person account of an incident involving a flinter. I would not recommend loading a percussion capper in that fashion. Percussion guns have a much longer flash channel and I can see the possibility of a lingering spark. That is not a problem for me since I have no interest in using one of them new fangled percussion guns
