So, I had 2 mis-fires out of ~250 rds this weekend. Sucks during a match. Kind of unusual with CCI Tactical. I had done my usual cleaning. So I got to thinking about what doesn't get cleaned and that's the firing pin / spring / firing pin bore in the bolt.
You have to drive out a roll pin to get the firing pin and spring out. It seems worth doing occasionally. There was a BUNCH of accumulated crud and S&Ws' design leaves no way to clean this area without driving out the cross pin and pulling the firing pin.
Seems it should be done once in a while judging from the amount of crud that came out. Just FWIW.
I have heard of folks using Gun Scrubber but I do as you did... break it down every so often & give it a good cleaning. I suggest using dry graphite as anything wet will collect more gunk.