Stainless steel is corrosion resistant not corrosion proof. My S&W revolvers do not have stainless steel trigger components. Stainless steel galls, does not through harden, is relatively soft compared to a tool steel. Some manufacturers do use stainless steel parts in the firing mechanism and I had problems with my Ruger MkII Stainless steel.
Last year I had taken the thing out to a full course 2700 match when in the slow fire stage of the NMC course, I was getting failures to fire!. The rim had a dent but round did not ignite. Luckily I had my Leatherman multi tool on my belt and I was able to remove the bolt. As I suspected, the firing pin was not going fully forward. Also, luckily, it is easy to take the firing pin out of a Ruger bolt. I took the firing pin out and I don't remember how I decided the problem was a mushroomed firing pin tang, but that was it. My multi tool has a file and I used that to file the back end parallel on both sides, install the firing pin, and got back in the game. Still I saved five rounds because I ran out of time.
I have only fired about 300-500 more rounds through the pistol when again I started having signs of a weak firing pin strike. This occurred in the rapid fire stages of the Bullseye match and I was able to complete all firing for the day.
When I got back I took the bolt out and noticed that now, instead of the end of the firing pin being mushroomed, it had deformed due to the hammer strikes. As you can see in the pictures below, this firing pin has deformed to the point that there is insufficient firing pin protrusion to reliably ignite cartridges.
The factory mainspring has never been changed out nor the factory hammer. The internals are all original factory. I have concluded that whatever steels Ruger used in my stainless MKII, they are soft.
Anyway I got on the web and ordered a Volquartsen firing pin, according to the description it is made of A2 steel, which is a tool steel that is easily through hardened. Most commercial stainless steels tend to be surface harden able with a shallow hardness depth. (not the knife stainless steels), but I really don't need rust resistance in this application, I need a combination of hardness and toughness. I installed the Volquartsen firing pin and the pistol went back to shooting them in the middle.