Actually IF you really need to carry that, I'd suggest .454 round ball though some sources might recommend a .451 round ball or some modern design bullets in .451. You want a balance of Muzzle Velocity and bullet weight. That soft round ball will work fine. BP isn't like modern powder, and compression isn't helping your powder burn as much as with a modern cartridge situation. Further, you have a trade-off between the amount of powder vs. the distance to the cylinder gap. While it is true that a bullet shaped projectile will seal the chamber longer than a round ball due to shape, the extra weight and longer length means less powder and velocity; plus the added friction of a modern bullet alloy along with the greater bearing surface, and you may be actually losing something from the combo. You might even find that the round ball deforms as well or perhaps better than the hollow-point in the modern alloy ..., IF you're not casting your own. Hollow points, even lead alloy, perform better with higher velocities than one often sees when using BP. I don't think there's going to be an issue of pass-through.
ALL of what I've written for your particular handgun is conjecture, based on what I've seen with my own handguns..., you really ought to do a chronograph test, and also a gel block test, to check for performance on deer and SD.
LD