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Modifying the hammer/sear jig for function testing: with a few springs and readily available parts, a stoning jig can be modified to allow the hammer and sear to function as they would inside the M1911 pistol, thus speeding up the smoothing process.

If you're like me--and I suspect you probably are--you're constantly trying to find ways to make something better, to improve its function, or to make it more versatile. That "something" might be a tool, a fixture, or a jig that you've purchased to improve the services you offer as a gunsmith. I do this all the time; my mind, it seems, is working on ways to improve both my own skills as well as the performance of my tools and fixtures.

Here's a perfect example of what I mean. I've always had trouble matching the hammer and sear surfaces on the M1911. There are fixtures on the market that will help you to smooth and polish these surfaces, and they work great. But these are "static" fixtures; no fixture that I know of actually allows the hammer and sear to function outside of the M1911 pistol. Seeing these parts in a static condition is helpful, but it seemed obvious to me that the fixture would be greatly improved if it allowed me to see exactly what was happening to these parts as they work inside the 1911. This way, any drag between the surfaces could be detected and corrected, thus greatly reducing the number of times the gun must be reassembled for testing.

When matching the hammer and sear, often the sear or the hammer is a little too high or too low on this corner or that. And typically, these parts are not as smooth as they should be. Moreover, it seems I can never get them square enough to satisfy my own standards of quality. Sure, I could buy matching parts from Wilson or some other quality supplier. But I like to do my own work, and I want the satisfaction that comes from knowing what I'm doing and knowing I can do it perfectly.

The fixtures available from Brownells (800/741-0015; www.brownells. com) work great for their intended purposes, but I could never get used to the Yavapai 1911 auto sear tool. Maybe it was my eyesight; I don't know for sure, but I sent it back with a note saying that it would be great if they sold only the magnifier. I didn't expect it, but a couple of weeks later the magnifier showed up. Now that's customer service.


The other jigs available include the Ed Brown 1911 sear jig, the Power Custom Series I Stoning fixture, and the Brownells trigger-adjustment pins. I can smooth and polish the hammer and sear and then use the pins to look at the results. One jig that I particularly like is the Wilson #5 jig. I purchased mine many years ago, and unfortunately it's no longer shown in the Brownells catalog. The Wilson jig is similar to the trigger-adjustment pins, except that these pins are mounted in their own base. This is the jig I modified for function testing of the hammer and sear, which is shown in the photo on the opposite page.

If you have or can find a Wilson #5 jig, you'll only need a few things to modify it like I did. First you'll need a 6- by 6-inch piece of wood about 1/2 inch thick, a 4-1/4-inch lag bolt, the 25x magnifier

from the Yavapai 1911 auto sear tool (Brownells #080-835-001DE), a set of springs--one for the hammer and one for the sear (Brownells #969-160-700), an Alley collimator extension (Brownells #034-101-000AB), and some nails or screws.

As you can see from the photos, the jig is straightforward. I drilled a hole for the lag bolt and countersunk it to make it flush on the bottom. I placed the collimator extension on the lag bolt using the last slot and secured it with the thumbscrew. (You can make a similar extension from a piece of aluminum bar stock, but I had this extension on hand for bore sighting scopes, so it was available.)

I then put a sharpened pencil in the third slot and held it close to the wood base so I could scribe a circular mark by turning the extension from one side to the other. Be sure the thumbscrew is not too loose, or else the arc will not be accurate. Two points on this mark are used for aligning the Wilson jig.

The position of the pencil is where the magnifier goes. This allows you to clearly see the mating surfaces of the hammer and sear. Two slots are carved out ensuring the proper placement for the Wilson jig. First, be sure of the alignment by putting a hammer and sear on the jig. Then visually see where they mate through the hole. Place the jig carefully on the base so the arc can be seen through the hole, and align where the hammer and sear mate. Scribe the edge of the jig. Carve out this dimension to the depth of the thickness of the jig.


I carved out two locations. The other location is so I can look at the other side of the hammer and sear. When placing the jig on the other location, turn the jig upside down. The photo above shows the jig reversed for looking at the other side.

Now that the fixture is essentially complete, you will need to place the two nails (or screws, if you prefer). You need to experiment with this part of the project. In the first photo, you can see where I placed the nails so I could attach the springs, one to the sear and one to the hammer.

The springs should be tight, but not so tight that they cause distortion in the alignment. One spring pulls on the hammer waiting to be released, and the other spring is pulling on the sear, which is holding the hammer from dropping. By manually pushing on the sear base, you will get the hammer to drop. If the tension on both springs is just right and you slowly push on the sear base, you should be able to feel if there is any drag. If it doesn't feel smooth, you know what to do.

With this part complete, you can now put the magnifier in the slot, move it to the right location, and see the mating surface by either raising or lowering the magnifier or the extension on the lag bolt. Then move the jig to the other side, making sure you turn it upside down so you can see the other side of the mating surface. If you wish, you can add another nail and spring so it will be functional on this side also.

There you have it. This jig has helped me and I hope it does the same for you. With a light touch and a bit of practice, any drag between the surfaces will be easily felt. There are any number of ways the Wilson jig can be modified to accomplish the same thing, but even if you choose to do it some other way, I trust I have planted a seed in your mind.
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Title Annotation:Tools & Tooling
Author:Grisafi, Joe
Publication:American Gunsmith
Geographic Code:1USA
Date:Aug 1, 2009
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