Anyone have one? I have one manufactured in 1928, about 90% condition. It's a shooter, and my son loves trigger time on it. This one was my grandfather's when he was a boy.
In a recent trip to the range the firing pin broke. Old guns are great, but parts are often impossible to find. The FN Trombone is even worse because only 150,000 were made, and not many were imported to the US.
I was considering relegating it to the safe, but was able to manufacture a new pin from 1/2" x 1/8" carbon steel bar stock. See the process for fabricating a new one below. My son is enjoying blowing through my 22 stash again.
Anyway, if you have one let me know your stories with them. Awesome little gun, especially running 22 shorts.
Here it is - 89 years old and used by 5 generations.
Broken firing pin:
Started making the new pin with 1/8" x 1/2" carbon steel bar stock cut longer than needed to hold it in a vise.
Next I used a bastard file to dress the bar stock; this cleans it up and also flattens all of the surfaces as the bar stock is irregular. I also took it down to the same thickness as the broken firing pin.
Using a dremel with a reinforced cutoff wheel, I rough shaped the pin profile. I made sure that it was dimensionally larger so that it can be fine tuned with a file later. I used the broken pin as a template.
Here it is with most everything roughed to the proper dimensions with rat tail files. Now to fine tune everything to get it ready for a rough fit. in the bolt.
Next step is to put fine touches in, such as the tip of the pin. The striking surface is beveled to about 1/32" at the face. The lug is also radiused.
Once it is fine tuned and fit to the gun, I fired a couple rounds to ensure it functions (i just pulled the bullets and dumped powder on a few rounds to ensure primer ignition).
If I were to continue using the pin without heat treating, it would eventually deform and become unusable. First step in heat treating is to heat the front and rear of the pin until bright red then oil quench it. I am not too concerned about the middle of the pin by the lug; the tip of the pin and the back are the only parts that take a beating.
At this point I lightly dressed the pin so that I could get it ready for annealing. This returns the surface of the metal to a bright silver. I then put a flame to the tip and rear of the pin until it flashed blue which is roughly the temperature needed for the metal to be tempered.
I dry fired it a couple dozen times to check for signs of mushrooming - all good. I suppose you could blue it at this point, but I am just leaving it as is because I kind of like the coloration from annealing. One final test firing and my son gets to shoot up all of my 22LR once more!