I've tried swabbing with plain water misted onto a patch, the Windex/alcohol mixture, and Butch's Black Powder Bore Shine. My best accuracy has come while swabbing with the Butch's BPBS, dampening a patch and running both sides of it down the barrel. Then I run a dry patch, both sides, and reload. I was able to get a 3 shot group at 100 yds. using 250 gr. Shockwaves that measured .550" CTC while swabbing with the Butch's.
This is the stuff that I have confidence in as of now.