When they are new the loading lever is (should be) fairly tight. But the more you work the lever, it will move easier.
My Uberti Walker has not been shot much, so it is still fairly tight. But it will drop some under recoil with heavy loads. My quick fix is the same as some others have already suggested. A small rubber band.

I use .457 diameter round balls. .454 diameter seals the chamber well enough, but I seem to get better accuracy with the larger diameter balls. Maybe because they provide more surface area for the rifling to bite into?
When loading, the shaved lead ring is heavy enough that it can jam up the action if you miss getting one of them brush out.

The cap & ball guns are great fun except for the black powder clean up.
And unlike the little .36 Navy models, the Dragoons and Walkers speak with some real authority. And an impressive cloud of grey smoke.