Trigger rebound spring problem. They are sold with different weights. But old gunsmiths usually just cut one ring off.
If that happens you get what you get. Sometimes single action is to light. Hasbeen
That too.
I'd usually cut them off a bit at a time until I got it where I wanted it.
Stoning the machine marks where that rebound assembly runs smooth against the frame is probably more helpful in getting a smooth action.
Lots are happy with a lighter action, but don't pay attention to "smooth". You ought to be able to feel the bolt lock into the cylinder in a slow double action pull.
