Sorry, I missed your question earlier.
I suggest going with the 19 ga. overpowder cards, and Overshot cards. I use the 20 ga. cushion wads, as they are less critical, and tend to expand when lubed or dampened IMHO, anyway. The overpowder card seals that smoothbarrel to keep gases from getting into your shot and destroying the pattern, or cutting your RB. The over shot card has to be tight to keep everything in place. Use an awl, BTW, to put a small hole in the center of that overshot card, or wafer, as I like to call it, to let air escape when you run that down the barrel. I do this while watching TV, doing several dozens or even a hundred or more in one settings. When I run low, I do some more.
The tight-fitting, over powder card will also push air down in front of it. Take it easy pushing it down on the powder. Otherwise, it acts like a high pressure gas hose, and breaks and forces powder out of the main charge through the vent, or Touch Hole. Most people close their frizzens to act as a block or catch for this powder, so it primes the pan, or put a toothpick or feather in the touch hole before loading the main charge and over powder card.
That overpowder card scrapes any powder residue left in the barrel from a prior shot out with it as the gun fires, but slides over the melted lube being deposited in front of it by the lubed cushion wad. This melted lube than softens the residue from the main charge that is propelling everything, including that over powder card down the barrel. In humid conditions, it is wise to wipe the bore with a slightly damp cleaning patch, followed by a dry cleaning patch before loading the next charge. In hunting conditions, you never know if the next shot will be fired in a couple of minutes or hours later. Dry that barrel between shots, so you don't ever have to worry about whether that charge will fire.