Try this:When you guys swab the barrel after every shot or whenever do you take the breech plug out or just swab up to it and pull back.
For shooting at the range, I put a .50/.54 caliber brush on the rod. and pass it up and down the bore between shots. Bullets, sabot's and patched balls seat easily. (Learned that shooting with a group of experienced guys at a rondevous shoot).
For hunting with BP, I put a felt donut under the jag, lubed with Crisco. When I need a second/follow up shot, one pass with the Crisco clears the fouling and allows the ball to be seated easily even with a tight patch. Didn't figure that out myself either :-(
In the good ole days, the mountain men blew down the bore, and there was enough moisture in their breath to soften the fouling, but it gets old on a long shooting session. And you need to get your breath in/out timing right.