DRY-FIRING: Going through the actions of cocking, aiming, and pulling the trigger of an unloaded gun is known as "Dry Firing." It can be useful to learn the "feel" of your revolver. Be certain the revolver is unloaded and that the gun is pointing in a safe direction even when practicing by dry-firing. The Ruger New Model revolvers can be dry-fired without damage to the firing pin or other components.
I would look at the back of the chambers after you have dry fired ever so often. Don't be surprized to see dimples at some point on the rim of the camber. If you want to dry fire to check the trigger take out the cylinder. For practice use a center fire. A 32H&R Mag makes a good single six to dry fire.
I don't care what the book says I know what happened to my new model SS 4 5/8" Single-Six 22.
Was it defective? I don't know. But I don't dryfire rimfire guns anymore. Would Ruger fix it? Yes I'm sure they would. It fires fine and cleaned up with just a little stone work. As flatgate said "JMHO."
That's when the transfer bar "takes" the energy from the hammer fall.
My simple test: Unload gun. Check to see it's unloaded, again......
Cock hammer, squeeze trigger and maintain trigger pressure after the hammer has dropped. Slowly release the trigger while watching the hammer. If the hammer moves forward as the trigger is released (which pulls the transfer bar down) then the transfer bar is "pinched" between the hammer and cylinder frame.
A bit of adjustment to the depth of the "relief" on the face of the hammer will rectify the clearance issue.