Many years ago I began fooling with old single shot rifles and of course one of the first things I did was break a firing pin. The instructions in the de Haas and NRA books recommended drilling a blind hole in the firing pin body and installing a newly-made insert into the hole with some sort of adhesive such as solder.

I did this and it worked for several years but eventually the insert broke again, flush with the front face of the pin body so there was nothing to grab for removal of the broken stub. What to do?

The rifle was an early Winchester low wall and its firing pin has a unique construction with a protruding bottom leg providing retraction, so it would be difficult to fabricate a new one. I determined to re-use the old pin body but in order to remove the broken stub I had to drill an access hole through the pin body from the rear, for the removal punch to enter.

Now I had a big hole in the rear of the pin body, staring me directly in the eye whenever I shouldered the rifle. Not very safe. This is how I solved the safety problem, I call it the 'top hat' firing pin repair because of the shape of the rimmed intermediate insert.

When developing this repair, I had occasion to also repair several high wall pins used in heavy BPCRS competition. In order to better ensure durability and easy field replacement if broken again, I assembled the parts with Black Max and also provided a second 'top hat' bushing with its matching FP nose insert cut to the same dimensions as the ones used in the repairs.

If the repair ever failed (at Raton or Quigley, for instance!) then the shooter could use a cigarette lighter, big match or similar to heat the pin body and twist out the 'top hat' with pliers; the Black Max melts at about 350F and the newly-applied Black Max will set up in a few hours after the spare top hat is assembled into the cleaned-out pin body.

This was 10 years ago and AAFAIK neither repair has failed yet and both these fellows shoot A LOT. IMO part of the durabiliity can be attributred to the slight cushion provided by the Black Max & multiple inserts as opposed to the solidity of the (obviously over-hardened) original firing pins. These BPCRs were brand-new rifles made by Ballard, FWIW, and this was 10 years ago.
Regards, Joe