Uh, your'e not stopping a trigger that has swung through a great arc. The target trigger moves almost an inperceptable amount, which is the ideal case.
For a good example, consider electronic triggers on some free pistols, where there is no "break" between the hammer and sear.
In the case of the older Ruger Single Actions, a fairly strong trigger spring arrests further rearward movement of the trigger.
It's much like a rifle with set triggers.