The ball just sits lower in the chamber. Someone may come in and recommend the addition of cornmeal but at 30 grains, I don't think you need it.
I don't use lube under the ball (between the ball and the powder) I put the lube over the ball.
I also lube the balls before loading by rolling them around in bore lube.
As far as the recipe for bore lube is concerned your post will generate a lot of responses. My personal lube is one toilet donut (the wax ring from under a toilet...I recommend buying new ones as the used ones leave a smell that masks the wholesome essence of black powder) to one pound can of Crisco. My recipe is a compromise because the toilet donuts no longer are made of natural products. And I really should be using lard rather than Crisco. Problem with lard is that it is too fattening. I used to shoot only .36s but now they are all .44s. I shifted to Crisco to try to get them back down to .36s.