They are safe, as all have said. The S&W safety system is such that you can cock the hammer with a round in the gun, hit the trigger with a pencil or pen to push it out of the cocking notch, and the gun will not fire. (presuming no one has gone in there and removed or altered any of the built in safeties doing "trigger jobs") I have seen this demonstrated with primer only cases in, and not one of them popped the primer. You have to hold the trigger back while the hammer falls or it will not shoot.
The block that looks like a transfer bar is actually a drop safety. It works the opposite of a transfer bar. It is up and in place when the hammer is at rest and drops DOWN when the trigger is pulled. It is there for in the unlikely event that the gun is dropped hard enough on the hammer spur to shear the pivot pin that the hammer rides on, and would therefore be able to go forward and strike the primer. This block would be in the up position and block the hammer from going forward far enough to do this.
This drop safety was added after WWII when they went to the "Short actions" and the old long actions did not have it, in that exact format. Per S&W there were some cases of the guns getting dropped, shearing the pin, and firing. So this was added.
The hammer rebounds and a block of steel is placed between the toe of the hammer and the inside of the frame to keep the hammer back unless the pivot pin shears.
Louie
