When I mess with them, I'm still making cartridges using nitrated paper wrapped around a wood former, but there is a commercial system with good instructions and video here: https://cartridgekits.com/

Typically, you don't need to break the paper before inserting in the cylinder: compression of the cartridge when seating the ball will split the cartridge, or the flash from the cap will burn through. I've not noticed any loss of consistency when using them, though they do tend to be a bit less accurate than match loads loaded as mixed components. I only make them with conicals (vs. round balls), and I'm sure this is a factor in accuracy.