Revolver Trigger Mechanism


The trigger assembly described here is composed of four parts plus pins and springs. While slightly unorthodox as compared to others in guns of this type, it is designed to function equally well in both open- and closed-bolt configurations. With only slight modification it will serve as a two-stage trigger for a full-automatic version whereby a short, light pull will fire single rounds, functioning as a semi-

1 automatic, and a longer pull against a heavier, stiffer spring will cause the gun to continue to fire as long as the trigger is held back. Needless to say, this would translate into a highly illegal firearm. Don't say I didn't warn you.

Two of the parts, the sear and trigger block, must be made from material capable of being hardened. The trigger requires no heat treatment and can be made from any available steel. The trigger bar is cut from 12 gauge sheet metal.

It can be helpful, in some instances, to make cardboard patterns or templates of parts such as these. These are placed on the material to be used and drawn or scribed around, leaving an outline of the part to be cut. It can be helpful to drill the pivot pin hole first and lay out the shape of the part around it. This is far easier than trying to drill a precisely located hole in a finished or semifinished part.

The trigger is cut from 1/4 inch flat stock.

The trigger blade is cut first. It can either be sawed into a narrow strip and the curve bent into it, or the front face can be formed with a 1 inch diameter end mill. This is done first simply because you need enough material on the other end to hold on to while forming it. The front face can be crowned or rounded slightly using a half round file or, if available, a high-speed grinder of the Dremel tool variety. The upper leg can be formed by milling or sawing it to shape. The only critical dimension on this part is the distance between the pin holes, and even this need not be exact. The rest can be shaped to suit the maker. The projection at the rear is only required for the full-automatic version.

The trigger bar is cut from sheet metal and formed into an open-ended rectangle by bending it around a 1/4 inch form block. This part should be cut slightly oversize and finished after bending. The tab at the upper center with the small hole should be bent to the rear at a 30 degree angle. The coil pull spring connects to this and not only serves as a trigger return spring but exerts upward pressure on the forward part of the trigger bar. Exact dimensions cannot be given since this part must be hand-fitted during assembly.

The sear should be wide enough, from the pin hole forward, to prevent sidewise movement when mounted in place. The leaf spring material suggested may not be thick enough for this. If material of sufficient thickness is not available, a spacer can be soldered or cemented on one or both sides to increase the thickness. These should encircle the pin in the same fashion as a washes which, when assembled, cannot work loose. Note that the spring pocket is all that keeps the spring in place during assembly, so it should be at least as deep as shown.

The trigger block, for lack of a better name, should also be almost as wide as the inside of the frame. This too can have a spacer or washer, but only on the left side as viewed from the rear. The small projection at the upper right hand corner is engaged by the notch on the trigger bar which pushes it out from under the sear when the trigger is pulled, causing the gun to fire. Here again, the overall shape is not terribly important.

While we are engaged in making these parts, we may as well go ahead and make up the magazine latch. This can be formed with the milling machine or sawed to shape from 1/4 inch thick flat stock. Here again, the overall shape is not that important. The pivot pin hole should not be drilled first as with the other parts but is drilled with the gun assembled and the magazine in place. The latch is pushed up firmly against the retaining notch in the magazine and the hole drilled. This will result in a near perfect fit without any cutting and trying, as is required when fitting some of the other parts.

With the parts in a semifinished condition, dummy pins should be cut long enough to go completely through the frame and protrude 1/2 inch or more from one side. Grind a slight taper on one end of these pins to allow them to enter the slightly smaller holes on the off side without undue resistance. The protruding ends should be rounded slightly. The trigger bar is installed on the trigger and pinned in place. Then, all the parts are installed in their respective positions but on the outside of the frame. It should be obvious what is required to fit these parts to a point where they work the way they are intended.

The only part that should require much fitting is the trigger bar. With the trigger block positioned in place under the sear and the trigger in an approximation of its forward-most position, the notch at the front of the trigger bar must rise into position behind the projection on the trigger block without binding. Mark the notch location and cut it back to the mark. When it seems to work correctly, the parts should be mounted in their respective positions inside the frame and tried. Springs can be kept in place during assembly by filling the spring pockets with wheel bearing grease. Too much metal removed from the trigger bar notch will result in excessive trigger travel. Removing a small amount of metal from the face of the trigger block will allow it to move forward, reducing the gap between the notch and the trigger bar projection. Several tries may be required before you get this perfect. But when, and if, you do, a short, light trigger pull will result.

If the two-stage trigger is to be installed, another notch must be cut some .060 to .100 inch behind the existing notch and approximately the same distance above it. The .065 wire spring is bent to shape and installed so that it almost contacts the projection at the rear of the trigger. This is simply to cause enough resistance to distinguish between the first and second stages of the trigger. The harder, longer pull against this spring causes the second notch on the trigger bar to push and hold the trigger block out of engagement with the sear, allowing the bolt to reciprocate freely. This will not work with the closed bolt in place since the cartridge rim will hang up under the firing pin, interfering with feeding.

One more time: this trigger mechanism, in combination with the open bolt, will result in an illegal firearm. I have described it simply to illustrate the principle. I do not advocate that you build one. The closed-bolt gun should be adequate for your needs.

Revolver Pistol Trigger Assembly
Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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