Fabricating Obsolete Gun Parts

I recently got involved with making some parts for a gun which the manufacturer no longer supports. The part is an internal extractor for a pistol that has a stamped steel slide with a breechblock that is separate and pinned inside. You have to remove the breechblock to get to the extractor, which is inserted into the block. One of the members of a forum that I frequent damaged the extractor in his pistol and then started to hunt for a replacement part.

After exhaustive pursuit, his conclusion was that he could only use his pistol as a paperweight as parts were nowhere to be found. I volunteered to help. His inability to find that part, which he posted on the forum, raised the concerns of many owners of that pistol and others in that series. That one small part could render many pistols useless with no source available.

One of the things I stress to gun owners is to save the broken part so a gunsmith will at least have something to physically measure and copy, even if it is in pieces. I was fortunate in this instance as I had the same pistol and could remove and measure the part so that I could reproduce it. Here are the considerations and processes that I went through which I hope will help other ‘smiths when faced with part reproduction. First, I had to consider the part itself; form, fit and function.

Having worked on pistols in general for some time, I realized that the claw geometry, spring tension, and relationship between the claw and breechblock face were the critical factors to consider. I sat down with calipers, micrometer, pad, pencil and calculator and went to work.

I have been involved with automation equipment design for many years and have a CAD (Computer Aided Design) system, so this allowed me to make a formal drawing of my part, but, believe me, I have and still work from pencil sketches, especially if I know what I am doing is a one-time deal. CAD work is very costly. Then came problem number two; at what tension do I set the extractor? The only way that I could figure how to put a number to the tension was to measure what it was in my gun.

The gun manufacturer considers that "proprietary" information and wouldn’t help with the specifications. Anyone who has worked on 1911 style pistols with the internal extractor knows how critical the correct tension is for proper case extraction. I removed my breechblock with the extractor and set it in a vise so the extractor was held in the same relationship as when in the frame. I took a digital fish scale, which I had previously modified to accept different hooks and added one appropriate for the extractor.

I then deflected the extractor .050" by pulling with the scale and took a measurement. The .050" was somewhat arbitrary but I wanted to be sure that at least the depth of the case groove was covered in the extractor travel and I wanted a distance that was reasonably repeatable. I made several repeated measurements and settled on a "number + some tolerance".

I was able to measure the tension from some other similar pistols at a later time to verify the tension and found that the 9mm and .40 pistols used the same tension, but the .45 ACP versions used a lighter tension by 2 to 4 lbs. at .050" My re-design takes into consideration the fact that the extractor is flat in its machined state, and then bent at a particular point and angle before hardening and tempering to give it the required tension.

deflection. I ask people to tell me what caliber they have when ordering an extractor and tension it accordingly. The tension is a function of the material thickness, which is constant as manufactured, the temper of the metal after heat-treating, which I also make a constant by using the same process temperatures, and the bend in the extractor. I vary the bend to change the tension; the more bend, the more tension because of the way it sets in the breechblock.

Now, because the extractors are "tough" and not brittle after heat-treating, there is a certain amount of tension adjustment that can be made after treatment, however, I found that when I make a batch and measure them for tension, they can be sorted by tension and only a few of them require adjustment. I want to take a jump back to the "form" of the extractor.

Once the part was measured I determined that by milling the profile of the part I could make strips containing multiple extractors, cut "blanks" off the strip and finish them up on my surface grinder in a fixture. Material selection for a particular part is important. I find that I can cover fit, form and function of most small pistol parts with either 4140 or 01 tool steels.

For some parts, either is definitely overkill but I have gotten used to working with these materials and the fact that they can be easily hardened and tem pered in a small shop without exotic ovens and controls is what initially made them attractive to me. Both materials are oil hardening alloys. They are also available in the round or flat and 4140 can be bought prehardened to Rockwell C 28-32, which is still machineable and needs no further treatment but is very tough. This is a time-saver for some components.

Obviously, we all have our preferences when it comes to working with materials and I have found that I can cover a lot of bases with these two and only vary when absolutely necessary. These keep stock to a minimum without sacrificing quality for the intended application. Also, in the case of this extractor, I need spring characteristics which can be obtained from both materials through the hardening and tempering process.

Once I settled on the material and produced the blanks from which the final parts would be made, I had to come up with some fixturing to allow me to hold the blanks while machining. The first was a very simple fixture, but adequate for proving out the design. I actually used this to manufacture four dozen extractors before making a better fixture. Having established my process and gaining some confidence in it, I made anew fixture that simplified set-up time.

This improvement allows me to hold the part more firmly because of the bar clamp vs. the cap screw on the old fixture. It

also allows me to readily set the angle for machining the tip of the extractor claw without having to reset for each extractor. Originally, I used the actual pistol breechblock and extractor to determine the extractor tension. Because the gun that I borrowed these parts from is one of my carry guns, I needed a breechblock substitute. I made a breechblock fixture using the same approach as for the extractor: Measure, draw (in this case, a pencil sketch) and machine.

I made it from 01 and made it rock hard, Rockwell C 50-55, as I knew it was going to be used for testing every extractor and I didn’t want these tolerances to open. The way the extractor fits the breechblock gives the extractor its preset or starting tension. After fitting to the test block I set it in a vise so I can use the scale to deflect the extractor for measurement.

To make my life a little easier, I made the hook of the gauge .050" thick and The new fixture simplifies set-up time, holds part more firmly due to bar clamp, and can used to readily set the angle for machining. This is the same as when using the actual breechblock for the initial measurements. The author deflected the extractor .050" to ensure the depth of the case groove was covered in the extractor travel. put a mark on the fixture; when the backside of the hook reaches the mark, I take my reading.

One other point, the gap between the face of the breechblock and the extractor claw is critical. The gap for these pistols is .060". I made the test breechblock dimensionally the same as the standard block so I can use a .060" feeler gauge to test this dimension while in the test fixture. Well, this all sounds like a lot of work to make an obsolete gun part but in this particular case the number of guns involved warranted the work.

Once all set up, I can now take a blank and my fixture and make this part on aper-order basis. I keep a strip of the profile available and several blanks to make my life easier and more profitable. When I run out of blanks, I cut a few more off the profile strip. After the first onslaught of orders, I now get a reasonable flow of requests, which has added nicely to my weekly work schedule and income. Conclusion There really is no reason for any pistol to become a paperweight.

A little analysis of the broken part for form, fit and function and some simple tooling will open new avenues for business. The word soon gets out that you are more than a "parts changer" and life gets a little more interesting! AG