Any idea how many shells you had thru that gun Zippy - when you found the problem / or how many yrs you had it at that point ??
As a note ... a few yrs ago, when a lot of guys were shifting to Chedite primers because we had trouble getting Remington and Winchester 209's ...there were some eroded and pitted firing pins showing up in a lot of Brownings. There was a lot of discussion about it on some of the more dedicated to clay target shooting forums ...and I don't know that there was ever a consensus, but it seemed to be related to Chedie primers ( corrosive, temperature, etc ...who knows)....
I currently shoot several Brownng O/U's ( and have shot the same 8 or 9 guns for the last 13 yrs or so ) and have not used a lot of Chedite primers -- and many of my primary guns are well over 100,000 shells with no firing pin corrosion issues ( primarily Win and Rem 209 primers ) in 12ga, 20ga and 28ga ( I shoot a .410 Browning O/U as well -- but despite the fact that the gun is probably 10 yrs old I don't have over 5,000 shells thru it probably )...