Watching the Alec Baldwin interview on TV last night got me wondering if a single action prop gun would fire by just releasing the hammer part way from full cock? I only own double action revolvers and I just tried it on my S&W M34 and the hammer does fall all the way forward without pulling the trigger.
On your model 34, there is a hammer block that will not allow the revolver to fire without the trigger being pulled, even when the hammer falls. I believe this is true of all modern numbered model S&Ws. Even those with the hammer mounted firing pin.
Likely wouldn't work on a j frame .22 because of bore diameter, but on any larger cal S&W revolver make sure the weapon is unloaded, cock it, and insert a pencil, eraser first into the bore all the way to the breechface and point the revolver up. If you pull the trigger with your finger, the firing pin will launch the pencil.
Repeat the exercise, but only tap the trigger with another pencil until the hammer falls, and the inserted pencil should not move. If it does move there is a malfunction in play.
I've only done this with .38/.357 revolvers. Don't think you'll get a pencil in the bore of a .22. And a .44 or .45 might be too large to center the eraser on the firing pin.