All good points craig. Quite honestly I'm hoping that the collective wisdom on this forum will be of great help (not that they haven't been up to this point). Even those on the forum with the most Meriden experience are unsure what the guts should look like. At some point I'll enlist the services of a gun smith, particularly to remove some dents from the barrels. Maybe also for the firing pins. Apparently, there aren't too many 20ga Meridens around (if any) so no one is able to tell me this is how it should be. Not sure a gun smith will be able to help more than those on the forum but you never know.
The receiver isn't threaded for firing pin seats so retaining the firing pins must be done by the stock and/or the side plate. It is my understanding that while not common it isn't unheard of. In looking at my receiver and stock, I can see how it is possible. As for a spring, I again understand that it is not uncommon for these old guns to not have one although it would be nice. Might be possible to figure this out as long as it will work with the retaining method that I end up using.
Agreed that it will be a trial and error process. I think that I can get close. First step will be to make the casting and see where it goes from there.
If you have any insight or wisdom you can send my way I sure would appreciate it. My guess is that you have a lot more experience than I have. For instance, your comment about piercing a primer intrigues me. I haven't heard of that but my guess is that it has to do with the FP projecting far enough to pierce thru the primer. Doesn't sound like fun. I seem to remember a rule of thumb relating to projection of the FP related to it's diameter (or something along those lines). Again, any advice is appreciate.
Kirk