When loading round ball, be sure to leave enough room for the paper to come half way up the ball, otherwise you risk dumping your powder and ball into your lubrication. Don’t ask me how I know.
It takes a few dozen cartridges to get the hang of things, but then things will go smoothly and you’ll be turning out perfect cartridges more rapidly. If you are not a patient person, consider a cartridge converter, but I find the repetition and flow to be relaxing.