This thins the pack out pretty quickly!
First off,
Let me start by saying $40 is a smoking good deal for a properly made firing pin considering the time and effort you are going to invest to make this thing correctly!
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Secondly, is the firing pin round or flat stock?
Flat stock is MUCH easier to work at home, but most of the firing pins from the era are going to be short and round...
When making firing pins for my 'old timers' around here,
I usually start with a piece of spring steel, and turn in in a lathe.
Springs from small import cars work great for stuff like this, no sense in trying to turn down some huge American made spring from a truck just to make a firing pin!
You can get them for cheap or for free at the salvage yards.
You will have to heat the spring and straighten it so you can work it correctly. That means a torch with some 'Gumption' or a small kiln and propane torch.
DON'T OVER HEAT THE METAL!
Dull red is plenty to straighten a section of coil spring!
The straighter you get it, the less it will beat you stupid trying to work it!
If you cheap out, you can use a section of bolt shank from a long bolt.
Cut the head and threads off the un-threaded part of a bolt, and use that metal for the firing pin.
Even a grade 8 bolt won't be as good of quality of steel as a car spring... But it will work.
Heat and cool the section of spring steel or bolt shank you have several times, letting it air cool, or if you have a small kiln/forge, let it cool in the edge of the kiln/forge.
This will soften the metal for working, and it's called 'Annealing' the metal. (pronounced A-Neal-ing)
If you don't have a lathe, you can spin it in a drill press and use a file or 'Dremel' type tool to rough it down into the general shape you need.
Once you get it to the general shape, you will need to go very slowly with files to get the precise shape you need for the firing pin.
I usually do the final fitting work with a comparator and a stick covered in fine grit emery cloth to get the dimensions exactly correct.
Remember to leave enough turned down space behind the pin to cut it off from the stock tail that is in the drill chuck...
Once the pin is formed and you are satisfied with it, then you are going to have to HEAT TREAT it...
(This is what separates the men from the boys!)
You are going to have to 'Normalize' the metal, that means heating it up until it looses all magnetism.
When a magnet won't attract the metal anymore, it's reached it's proper temprature...
You need to 'Quench' the metal in oil or lard that is about 100°F, and be prepared for FLAMES! They always flair!
I keep mine in a pan with a lid so I can snuff the flames out.
I used to use lard & oil, but it goes rancid and stinks to high heaven!
Now I use mostly automatic transmission fluid, some engine oil, and some paraffin as a mix, but I don't think you will need anything but ATF (Automatic Transmission Fluid)
Remember, your firing pin MUST go in Point first!
The first part to hit the liquid will be the hardest, and the point of the firing pin should go in first!
Now your pin is at it's 'Hardest', and it's BRITTLE!
If you try and use it now, it will break!
You need to 'Draw Back' the temper of the metal a little...
This is done by Re-Heating the pin, and 'Quenching' it again...
This time you don't heat it up as much, just until it starts to barely show some color, and quench it in 100°F oil...
And let it lie in the oil until you can retrieve it with your fingers.
Once you do the retrieval, then you can cut off the excess and polish it out...
You should really make more than one when you do this,
You will be VERY surprised how often they will break when they hit the quench oil!
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I wouldn't make the long, slender firing pins found in todays firearms like this, but for the older, shorter, thicker pins, this works VERY well...