Fabricating Firing Pins

When dealing with older firearms, consider yourself lucky if you can find a replacement part that will fit the gun you are working on to achieve correct function. Most likely, to find what you’re looking for, you’ll need to go to a parts broker, who "parts out" used guns and then sells the individual parts. There’s no guarantee, of course, that the used part you find will work correctly in the gun you’re working on.

And it’s especially frustrating when the part you receive is more worn than the part you’re trying to replace. If you have the original part, it can be used as a pattern for making a replacement part’even if it’s badly worn or broken. Or, if the part is missing entirely and you can find a replacement part from a parts broker, that part can become your starting point for making anew one which can then be fitted correctly.

Firing Pin Materials One of the most common jobs I get when working on pre-1960 firearms involves broken or lost firing pins. Some customer’s kid has taken his old gun apart, and now some of the parts have wandered off and can’t be found. They usually want to know what it will take to get the gun back into working order so the kid can take it apart again. My normal response is: "Bring it in and I’ll see what I can do." The most common firing pins are either in round or flat configurations.

The round-style firing pin are most common, and these are relatively easy to make. In fact, they can be so easy to make that I once pulled a firing pin out of a Remington Model 8 rifle and found that it had been made from a 16-penny steel nail. The flat-style firing pin can get quite elaborate. A good example is the firing pin found on the Remington Model 12 .22-rimfire slide-action rifle before serial number 650,000. In fact, that’s the example I’ll be using here.

I decided that a replacement should be made when I discovered a break on the thin outside/inner wall of the original.

This firing pin not only acts to detonate the primer, the front end of the firing pin also acts as the ejector, putting pressure on the rear face of the spent cartridge case while the extractor pulls it from the breech. (As you may know, when the Remington Model 12 transitioned into the Model 121, the breech bolt changed and around firing pin was employed.) There are a couple of readily available steels to use as base material for fabricating new firing pins.

A good tool steel, either 0-1 or W-1, is easy to machine yet tough enough without having to go through a heat-treating process. La Salle fatigue-proof steel round stock is also easy to machine and makes fine firing pins, screws, and assembly pins. Some of the milder, low carbon steels will work as well, but they should have the front and rear working ends treated with "Kasenit" to add carbon to achieve a better degree of toughness. All of these steels are available from Brownells.

Measuring And Machining After checking first to see that the chamber is empty and the magazine has been removed, we need to disassemble the firearm to the point where the bolt is removed from the receiver. Anytime you’re working on a gun part that involves springs, a good pair of safety glasses should be in the correct position on your face. Remove the retaining pin that keeps the firing pin in place. Contain the spring as the retaining pin is removed, in the event it comes out quickly.

It helps to make it a habit of measuring the firing pin completely and drawing a basic outline of its shape. This doesn’t need to be a fancy blueprint, just good enough to give yourself an idea of what you’ll need to make. A caliper or 0-1 inch micrometer will get you through this step with very accurate results. Transfer your measured findings to the appropriate parts of your drawing. It’s important to look the firing pin over for any obvious signs of wear.

Look at any of the chamfers (angled areas) to see if there is abnormal wear in these areas, which could mean there is some battering going on inside the bolt. This would indicate that this area on the firing pin is either too long or too short. Round firing pins are best turned to size in a metal lathe, but a creditable job can be done with the raw stock mounted in a drill-press chuck.

One caution here: Don’t put excessive side load on the workpiece, as the chuck shank is normally held in place by means of a tapered bore. Too much side load or pressure from a file could disengage the drill chuck from its place in the spindle. Flat firing pins are best shaped in a milling machine, but here again, a drill press with a true-running chuck could also be used if you have access to an X/Y cross vise.

You’ll need to take light cuts with the end-mill to prevent creating excessive side load causing the chuck shank to disengage from the quill. With some time and patience, along with a drill press and file, a very workable flat firing pin can be turned out. Using the firing pin depicted in this example, the firing-pin returnspring slot can be made by drilling a series of holes and then using around needle file to connect the holes and get the slot into the required shape.

Using a Jig When you need to make several firing pins for the same model firearm, a jig of some sort would be very helpful for reducing setup time. I spent a couple of hours making up this jig to hold the older-style Remington Model 12 flat firing pins during the milling stages to get the firing pin into a semi-finished state. This jig is made out of aluminum so that it will not distort the workpiece as it’s held during the milling operations.

The raw stock for this firing pin started as W-1 flat drill rod, 3/16 by 3/ 8 inch in size, cut to a length of 2-3/16 inches. This piece is then milled on both ends to clean up any irregularities from sawing and finished at a length of 2.150 inches. The final dimensions after all four sides have been milled flat and square is .150 inch thick by .320 inch wide. The firing pin blank is then clamped on its sides in the aluminum jig, which has a slot .312 inch wide by .050 inch deep milled in the middle

between each half. A dovetailed undercut was made along each side wall of the jig to remove any radius in the bottom, lower corners. This allows the firing-pin blank to lay flat in the bottom of the jig groove. Two #8-32 screws were used to clamp the halves of the jig tightly together and hold the blank in place. In this position, the through slot for the return spring was milled in the middle of the firing pin blank with a 5/32-inch-diameter endmill to a length of .700 inch, .312 inch from the back end.

The front end of the blank was then reduced in height to a thickness of .070 inch for a length of .650 inch. A 1/8-inch ball-end mill was then used to blend the transition from the difference in height, eliminating the sharp corner between the two thicknesses by creating a 1/8-inch radius between the steps. On one outer face of the jig a pocket was milled to nest the firing pin blank at a 25-degree angle.

This pocket will hold the blank firmly so that the notch can be milled in place for the firingpin stop pin in the bolt. A little clamp was made up to hold the blank tightly against the pocket wall. Each end of this jig has had an angle milled in place. One end has a 7degree angle, which sits flat against the bottom face of the milling vise while being clamped in the vise jaws. Figure 1.

The firing-pin blank is mounted in the groove in the top of the fixture, this time with a small strap-clamp across the top of the blank to prevent tool pressure from pulling it out of place. With the jig in this position, the tail at the rear of the firing pin can be milled to width, depth and thickness. At the opposite end of the jig another angle was milled at 15 degrees to create the necessary angle on the end of the tail.

The tip of the tail with the 15-degree angle is designed to hit a folded-flat spring mounted in the front face of the trigger-guard frame, causing the front end of the firing pin to act as the ejector and putting pressure on the spent cartridge case allowing the extractor to pull it from the action. Keep in mind that this jig is designed to get a rough blank into a shape that will require minimal fitting, but there is still some fitting to be done.

Figure 1 shows some of the areas where the semi-finished firing- The area at "A" should be fitted to clear the rear bolt face. Adjust at "B" to get correct firing-pin protrusion. pin blank will need attention. A nice finish can be obtained by using fourinch Swiss-pattern pillar files in the #2 and #4 cut. These files have "safe" sides, which means they have no edge teeth. Only the upper and lower faces cut; the sides are smooth and will guide the file without cutting.

For most all .22-rimfire rifles, firing-pin protrusion past the boltface should be around .035 to .040 inch. To measure how far the firing pin is protruding out the front of the bolt face, push the rear of the firing pin until the rear end meets the rear face of the bolt, and then measure the amount the tip protrudes past the front of the bolt. Adjust as necessary until you reach the required protrusion.

Conclusions Any time anew project is approached, it helps me to go over the required steps several times in my head. Thinking the project through from start to finish will usually show where any flaws exist in the plan, thus saving time and trouble later on. In this particular case, these firing pins were not that difficult to make after this careful planning, and, of course, by going slowly and measuring progress as the project went along. I