Several have mentioned the hammer nose breaking off. I remember talking to a gunsmith back when all Smiths had hammer mounted firing pins. He said that he frequently got Smiths in for repair with that exact problem where the pin broke during dry firing.

It can happen. I prefer to not subject my Smiths, or any of my guns to dry firing.

Some say use snap caps. I have also heard of people forgetting they replaced snap caps w/live ammo.

Therefore, the only time I pull the trigger on my guns is at the range.