I think there is a misunderstanding of what the hammer block does.
The hammer block keeps the hammer from moving forward when it is uncocked. At rest. the thing it does is prevent the gun from firing if it is dropped on the hammer when it is UNCOCKED. If the gun is dropped on the hammer, it can break the tip of the trigger, or crack the hammer, and fire if the hammer block was not there. It works sort of in reverse from a Ruger style transfer bar. To be honest, I think the smith system is more reliable. See my comment below about dry firing.
In WWII there was a sailor or Marine that dropped a Smith revolver and it fired, killing someone. The hammer block was mandated after that. This is the story I have heard about why it came about. Perhaps it is correct, perhaps not. The hammer block does however prevent this from happening.
I've dry fired several Smith revolvers over a 20 to 25 year period and have not broken or damaged anything. I would recomend snap caps if one was going to do this, but I have not ever used them. Empty shells with primers only last for a few hits each until they are dented in enough that they don't do anything.
I've broken 2 transfer bars in Ruger Single actions. 2 different guns. the transfer bars broke in the same place on each. I no longer believe the old story about Rugers being indestructible. When the transfer bar breaks, you are done. The gun will not fire. Period. End of story. I might still believe if I'd only broken one, but two is more than "a bad part" or an isolated incident. If you look at the transfer bar, it really isn't all that heavy duty. To function, it takes the impact of the hammer strike. The Smiths hammer block is more passive, it only works when the gun is at rest, and has no impact upon it. I now think smiths are the more reliable of the two designs. I prefer the Ruger SA's for heavy loads, but speaking strictly of funtional reliability, I prefer the Smiths now..I have a K-22 with well over 200K rounds through it and it's still going strong.
Deerinator, I'm going to tell you that the 357 is OK for deer at the ranges you mentioned, but I'd stay closer. I'd feel better at 50 yards or less with a 357. Others may have differing opinions. I'd prefer a larger caliber for deer. If you do use it for deer, I'd use the heaviest bulelts that will shoot well in your gun. Try the 180 grain loads. I would't use any 38 spl load for deer.
I'd rather not say how far I've shot at and killed game with a pistol. Everyone has their own limitations. Only you know yours for sure, if you are honest with yourself. I would recomend small game hunting with your pistol. Beside being a heck of a lot of fun, it's about the best practice for medium or larger game hunting. I've never used anything but the issue sights on my pistols.
I've shot a 6" group @100 yards off the hood of my truck with a 6" model 29, but that is a not field shooting position. the guns are pretty accurate, more so than many will think or admit. The problem is when hunting, you don't have a good steady rest, and a bad shot can mean miles of tracking, and perhaps losing, the animal. Get as close as you can. If you're not sure of the shot, don't take it.