There are some issues with the frame mounted firing pins you should be aware of. IMO the benefits outweigh the issues so it's not a problem as long as you are aware of how these firing pins can be damaged.
1) Snap caps and dry firing. I know, the manual doesn't state that snap caps are needed but I think the manual is WRONG. With the factory firing pin the forward position is controlled by the pin that restrains it in the frame. As a result, every time you drop the hammer without a snap cap or live round in the cylinder the firing pin strikes that retaining pin. Dry fire a lot with a factory firing pin and there are 2 possible results.
One is that the firing pin will break in the middle. If that were to happen during live fire the front end could pierce a primer.
Two, the retaining pin could shatter or bend. If that happens it could cause the firing pin to jam in the forward position because the return spring is rather weak. As for that shattered or bent retaining pin, removing it will likely require Wire EDM machining, a process I expect would run about 100 dollars.
2) Use of aftermarket firing pins. There are non factory firing pins available in extended lengths that also feature extended travel notches. These work very well in a revolver that has had the mainspring tension reduced but are an invitation for a pierced primer in a revolver with mainspring tension at factory original levels. I use these firing pins and they provide perfectly reliable ignition with reduced DA trigger pulls but I would NEVER use these firing pins in a revolver with full factory mainspring tension. Bascially, if you want an 8 lbs. or less DA trigger they are a great choice, however with any trigger set to more than 9 lbs. you're inviting a pierced primer. Below you'll find drawings that I made after measuring the factory firing pin and a Cylinder & Slide firing pin, note the length and position for the notch for the retaining pin.
Now, I'm not saying that either of these factors had any effect in your issue, you've never mentioned if you had dry fired your 629 extensively before taking it to the range. If you didn't, the most likely cause was pure bad luck. You may have got a firing pin that had an internal flaw that wasn't visible, fact is these parts are NOT X-Rayed for internal flaws and we couldn't afford these guns if they were. It's even more likely that you had a primer cup that had a similar non visible flaw. The simple truth is that commercially produced steel can have hidden internal inclusions in it and on rare occasions we get "bit" by the results. The good news is that it's pretty rare today but it can happen.
