I was trying to shoot small groups with a Ruger #1 single shot rifle from the bench and as I squeezed the trigger and the sear released, the hammer fell but the round did not go off.
The image in the scope jumped a couple of inches from the vibration caused by the hammer fall. I dry fired it on purpose again just to see that again. That kind of explains why that gun can shoot small groups but it's very sensitive to what point you rest the gun on and how firmly the stock is held.
Suddenly, a lightened hammer makes sense, and there is an aftermarket lightened hammer available for these rifles.
An extreme example of a gun that jumps due to "hammer fall" is a spring air rifle. Virtually all of these gun's recoil is due to the motion of the piston that compresses the air as the gun fires. In order to get consistant point of impacts out of these, the shooter has to learn to hold it in a consistant manner and just allow the gun to move unhindered during its firing cycle.