A question arose concerning the safety mechanisms of various single actions. Here is sort of a photo guide:
Two Ubertis, left hammers has the hammer block safety, gun on the right does not:
The hammer block is activated by placing the hammer in the safety notch (first notch) position. The one on the right will have the "Swiss Safe" type system, with two notches on the base (cylinder pin) pin. To engage this it is necessary to place the hammer at the loading notch, then depress the base pin latch and push the cylinder pin forward to engage the second notch in the base pin. Draw the hamer to full cock, then ease it down to the half cock to prevent cylinder rotation.
The one on the left is a Three Screw Model, the one on the right is a New Model. The Three Screw model can only be carried safely with an empty chamber under the hammer. The New Model has the transfer bar and may be carried fully loaded.