I watched a video of a cat using a sharpened case to punch out card wads. One wad over the powder and one over the shot....light crimp to hold it together. Since you're not loading in a revolver, no need to worry about recoil unseating the other rounds in the cylinder. Might work.Capsules to make my own.
I have some .45 Colt shot loads that use gas checks but they become a projectile of their own. Good luck with your project.