RE: American Pioneer Powder: Is it for real?
Switch to a bore brush, dampen the patch more - especially the four corners& only swab after every 2nd shot. The brush gets into the rifling better to remove crud thenwetness with both sides of the following dry patch. It also has a nub at the tip that keeps the bristles from reaching the breechplug face. Jags have a tendency to get right to the plug face. After around 5 shots, a buildup being pushed down after every shot could reach the center fire hole of the plug.
When spraying from a windex bottle, try to leave a small dry spot on the patchat the center point of the patch where the nub of the brush goes. It's not really important with any powders but the sugary base of Pinnacle, APP & Shockeys. That's why your bottle label requests not using anything wet like solvents that don't dry in a hurry.