Don, I woke up in the middle of the night, thinking about this. The previous person to work on the gun said he f filed a "burr" on the safety. Not sure where that was supposed to be - will ask him later in the week when I see him.
The firing pin moves perfectly freely. No bumps, drag, friction, it just goes in and out perfectly. What I was thinking, is what if something on the safety is creating the problem?
Two things I can try. First, to take two shots with the safety "on", then turn it "off" and see if the next shot is good.
Second, unless you tell me otherwise, I can move the safety lever just the tiniest amount, so it no longer appears to be rubbing on the top of the firing pin. Maybe that will cure the problem. Don't know, just speculating.
If either of those ideas seems to improve the gun, I have a new 'safety' on the way, not filed on, not modified, just right from S&W; it's a new part, not. used.
While fiddling with the safety last night, I turned on the safety, but used a small punch to press on the firing pin. It moved a tiny amount, then wouldn't go any further. I know the safety is supposed to block the hammer from hitting the firing pin, but what might be going on inside the device? Why would the firing pin not move inwards, when the safety is on? Maybe whatever this is, it could also be the source of my problems.
I ordered a new set of brass punches, and one of those devices that supports the gun while you're removing pins. About time I got one.
Finally, in the back of my head, I'm wondering if the people before me put in a firing spring that is too stiff. The springs I got from Wolff say "Firing Pin Spring EXTRA POWER". If for any reason my firing pin isn't coming out as far as it should, this could help. But it's the opposite of what I need, if it's preventing the pin from reaching the primer with enough force.
Installing the proper mainspring should help with all this - instead of light strikes on the primer, quite often there were NO strikes on the primer, which sounds impossible. Something has to be preventing the pin from reaching the primer properly, and without knowing enough about this to really comment, the safety looks like the only remaining part. It's making the gun safe when it shouldn't be.
......added later. If the safety isn't allowing the firing pin to come out all the way for the next "hit", maybe the extra power firing pin spring might be worth testing. I guess I need to start checking this after every shot, that the firing pin is out as far as it should be.