Wait! You have to remove the hammers to replace the firing pins which means a complete disassembly for all intents and purposes. For the uninitiated, replacing the hammers and reassembling a nitro special can be just this side of impossible. For a simple design they can be very tricky to put back together.
Just giving you a heads up, trying to save you some heartache. Unless you want to invest in some good and specialized tooling to do the job you may be better off to find a good gunsmith near you who has worked on one before.
Best, Dan