Ed,
I can't say I've ever seen one with a broken firing pin. I've looked at a bunch of them, and the design is similar to the Western Arms gun, and has things in common with the NID.
I haven't seen any of those with broken firing pins, either.
What, exactly, does "prone" mean in this case? How many have you seen with the alleged broken firing pin? How many have you fixed?
I've seen and been around A LOT of Nitros, the great majority of them had been beat to hell, but, they all, to a one, still worked. The main problem I've seen is a few loose Nitros, which, considering the condition they were in, is to be expected.

Do tell, Ed.

Keith, thanks for the input. Ken did a great job, considering the barrels I sent him were not in good shape at all, due to the external rust. I know you like your guns flawless (this one isn't) but, it will get hunted a bit and used. I will enjoy it.
Absolutely no non-sense about short chambers, low pressure this, or too tight chokes that.
Probably nothing about broken firing pins, either, but, we will see I guess.

Did you ever find a stock for your Nitro?

Best,
Ted