I have been playing with my 1858 Remington lately. The paper cartridges work fine with round ball. I tried the Johnson and Dow bullets, and boy do those shoot well. But I would have to modify the frame and plunger of the revolver to load those with the cylinder in the gun. I can still make paper cartridges with them and load the cylinder in my press.
Video posted here
https://youtu.be/CWTiRzbpRpI
