Shop Work: Hammers and Triggers and Sears, Oh My!

Few gunsmiths are lucky or rich enough to have a precision grinder, lathe and milling/drilling machine set up and ready to go their shop, cellar, or garage. This is the first in a series guiding those like them in the proper use of readily available, commonly used gunsmithing hand tools for the maintenance, repair and safe modification of customer guns. Today’s subject: Stoning the hammer and sear of a Colt Model 1911 and its close clones for lighter, or heavier, trigger pulls with hand tools and a jig.

The engagement angles between the two components sit at the top of the list when it comes to trigger work on a Model 1911. But why even mention the sacrilege of increasing trigger pull? Have you ever heard of sear bounce? In the 1911, not to mention other semi automatic handguns, this happens when the engagement surfaces between the hammer and sear are reduced to the point that the sear literally "bounces" out of contact with the hammer under recoil.

With nothing to get in its way, the hammer keeps right on cycling back and forth with the slide. The gun goes full auto. No one can say for sure where its muzzle will end up when it does. This occurs most often after the pistol’s owner, having become dissatisfied with the trigger pull, tears the gun down and goes after the hammer and sear with a file or handheld rotary power tool.

By using a fixture and a much more prudent 4 Not shown are Brownells India stone #MF 46 or FF 46 — which should have a three-inch strip of shim stock epoxied to its lower surface to protect the roller — and the supplied Allen wrench which fits the adapter tightening screw located on the opposite side of the adapter. approach you will avoid making the same mistake.

In my opinion, primarily because it can be used to rework so many different handgun triggers, hammers and sears safely, the fixture pictured here is absolutely indispensible. The brainchild of an original member of The American Pistolsmiths Guild, Ron Power has a small army of his fellow Guild members employing his fixture in accomplishing their precision trigger jobs.

As you might suspect, customers willing to pay the asking rates on a custom-built handgun from an American Pistolsmith Guild member area particular lot with very specific criteria so this speaks volumes on the quality of this jig. 1 2 3 Make a note of my following reference to "stoning." No files or motorized hand grinders are involved with a Ron Power Stoning Fixture. Note also that there are two different fixtures of this design to choose from.

Because I think it is simpler to use and put to work I prefer his Series I, but the Series II is equally precise and can be even more versatile. A set of feeler gauges available at most hardware and auto supply stores is required for both fixtures along with a #10 machinists clamp. A C-Clamp substitute for the same. The Series I fixture calls for a perfectly-square six-inch by half-inch stone. I use a fine India for my initial passes and a hard Arkansas

Above left and One is the letter "O" with additional lines to each side for initial positioning of apart and the second is an "H" for positioning a hammer. for finishing up. If I feel a need for additional polishing, I tight-wrap crocus cloth around the Arkansas and make a couple or three more passes. Unless ordered in otherwise, the Series I ordinarily arrives with one hammer/sear adapter suitable for Colt Government, Colt .380 and the Mustang.

Considering these days even rifle and shotgun manufacturers are selling their own clones of John Browning’s grand old pistol, it seems that not even the Department of Defense-directed switch to the Beretta Model 92 can kill off this design. 1911 pistols are among the most likely to be brought in by customers for custom work so this is an ideal adapter to start with.

As you expand, Series I Hammer/Sear adapters are also available for the Browning Hi Power; Hi Standard Auto; S&W Models 39, 59, 639, 659, 422, 622, 2206 Series; Third Generation S&W Series; and Ruger MK II pistols. Trigger adapters can be ordered for Ruger New Model Single Actions; Ruger Double Actions (Speed and Security Six); the Colt Python and MK III; S&W K, L, N, and Jframes; and the Ruger Red Hawk.

There are also adapters especially designed for the Ruger The flat must be secured slightly above and exactly parallel with the upper surface of the padded vise jaws and the polishing stone held parallel with the flat. A 10/22 and 77/22 .22 rimfire rifles. Every fixture comes with ample instructions. Are you beginning to appreciate what I mean by versatility? And that’s with no mention of the Universal adapter available only with the Series II fixture.

Using a Stoning Fixture Since it’s the star of this particular show, I’ll start off with a more complete introduction of the Series I. Re

2 All holes are provided for checking engagement angles during and after stoning. fer to the accompanying photos to become better acquainted. Smooth and polish both sides of the hammer as well as its flat with a fine, square Arkansas stone. The adapter is then set to the "H" position and held there via its socket head screw. A C-clamp or machinist’s clamp is used to keep the hammer in place against the adapter. All stoning must be done with the parts similarly secured.

Coat the ends of the 1 4 3 hooks with an indicator. A black magic marker, permanent variety, works for this very well for this. Rotate the elevator wheel 20 clicks to raise the stoning roller. While there is some set up time involved, a fixture allows a level of consistency that would be very difficult to duplicate by hand. Rest a .020" feeler gauge on the hammer flat before starting to shorten the hammer hooks. Snug the gauge up against the base of the hooks.

Keeping the India stone perfectly even on the roller and hooks, make one or two light one to oneand-a-half-inch strokes to confirm the black marker is being removed evenly from both hook ends. If it is you’re good to go on. If not, raise or lower the roller with the elevator wheel, re-coat the hook ends and try a couple more light passes until you reach "go." Keeping the gauge snugged against the hooks, make your stoning passes in a back and forth manner of about one-inch in each direction.

Do not cut the hooks shorter than the .020" gauge allows for a hard ball pistol and switch to the Arkansas stone for one or two passes for finishing them off. Reposition the adapter by rotating it so you can stone a very slight bevel on the inner tips of the hooks for sear clearance. Once this is complete, loosen the adapter screw, rotate the adapter to the "O" position and remove the hammer. Replace it with the sear to stone its face angle. Tighten the

adapter on the fixture by hand and coat the face of the sear with magic marker. Clamp the sear against the adapter and make a couple of short, one-way India stone passes. The marker coating should be evenly removed. If it isn’t, recoat the face, adjust the adapter in either direction and make another light pass or two. You have to keep doing this until the marker is being evenly removed across the entire face of the sear before further tightening the adapter with the hex wrench.

Make about half a dozen back and forth passes with the India stone. Switch to the Arkansas stone and Starting from left, the sear is in the face stoning position (A), the sear relief stoning position (B), and the hammer hooks are set for stoning depth (C). Even with a good fixture there is much reassembly and readjustment to get it perfect. make a few more lighter passes to evenly brighten up the face. Don’t change the adapter position. Remove the sear and turn it around to stone the relief angle. Work carefully.

When the angle looks sharply cut and brightly polished remove the sear. Install the hammer and sear pins through their related parts and insert the pins in their respective holes in the fixture base. Inspect all engagement angles of the sear and hammer under magnification. Reinstall the parts in the gun and make sure all safeties are functioning. There’s considerable taking apart, putting together and function checking with dummy rounds to trigger work. Get used to it.

If the pull feels heavy when you think you’re finished — well over four pounds — you’ll have to re-stone hammer and sear by raising the roller up a click or two on the elevator wheel. If it feels light, 3 pounds or less, increase the pull weight by lowering the roller. During all these re-stoning operations don’t lower the hammer hooks on a hardball gun more than .020 and be very wary of excessively shortening a sear in any case.

Once you become familiar with the Series I fixture you can gain a good feel for how many clicks up or down of its elevator wheel will increase or lighten pull weight and by how much. A Series II fixture, not discussed in depth here, makes trigger work more precise on a still wider variety of guns. The author owns both. Regardless of jig or tools used never forget that a target trigger pull in a .45 wad gun calls for a lighter recoil spring and hammer hooks cut lower than in a hardball or defensive gun.

Heavy springs, poor engagement surfaces and too short hooks are trouble waiting to happen. Remember what I said about sear bounce? AG