Smoothing A Smith & Wesson's Action
September 23, 2010
I've noticed that there's often misunderstanding about what's involved in a number of gunsmithing procedures.
Some old revolvers have rough or inconsistent trigger pulls. Extensive use of a revolver can cause the double-action pull to become rough and heavy. Even dried, built-up grease and oil can cause an inconsistent trigger pull. The remedy is simple.
I've noticed that there's often misunderstanding about what's involved in a number of gunsmithing procedures. For instance, "tuning a rifle" can mean a lot of different things to folks. To some, it's nothing more than adjusting the trigger; to others, it involves bedding the action. Then there are those to whom it means recutting the threads on the action, swapping out the barrel, bedding the barreled action, and rebuilding the trigger.
It's the same with revolvers. For a lot of gun owners, "smoothing the action" of their favorite Smith & Wesson revolver consists of nothing more than swapping out the factory springs with an aftermarket, reduced-power spring kit. Now don't get me wrong, this can give the revolver a better feel. However, there's a big difference between a light trigger pull and a smooth action.
In a smooth action, a consistent amount of force is required to cycle the mechanism. The important word here is "consistent." As you squeeze the trigger, you shouldn't feel increased resistance at some points and less resistance at others. The force required to squeeze the trigger and cycle the action should be as even and consistent as possible throughout the entire process of firing the revolver.
Resistance in the action cycle is normally caused by the moving parts encountering greater friction. This friction can be caused by surface roughness on one or more of the parts. It can also be caused by damaged or improperly fitted parts. It can even be caused by improper lubrication or the buildup of fouling, hardened grease, or oil.
A common misconception is that as a gun "wears in," it will naturally become smoother, and the action will become slicker. While that can happen sometimes, it won't always work out that way. I've seen a lot of well-worn and rough old handguns. While wear and use can gradually remove burrs or machine marks left on parts, excessive wear can make the internal contact surfaces rougher or change critical angles of contact among the parts.
In a typical double-action revolver such as the Smith & Wesson K-Frame, whether old or new, there are a number of major points where excess friction can develop. The first is between the trigger and the double-action sear on the hammer. The double-action sear is a small lever pinned to the front of the hammer. As the trigger is squeezed, the bottom of this sear moves across a flat surface on the top of the trigger. Any roughness between the sear and the trigger will increase friction and make it harder to squeeze the trigger and cycle the action.
A second important component that often affects smoothness is the rebound slide. This is a rectangular block located behind the trigger inside the frame. A rebound spring fits inside the rear of the rebound slide and is held in place by a vertical pin in the frame. The trigger, located in front of the rebound slide, is connected to the rebound slide by the trigger lever. As the trigger is squeezed to the rear, the rebound slide is pushed backwards by the trigger lever. Any roughness on the bottom or sides of the rebound slide where it contacts the frame will make it more difficult to squeeze the trigger. Even roughness on the inside of the rebound slide in the rebound-spring hole will inhibit the compression of the spring and make the trigger pull harder and uneven.
There are many other points of friction, and you would certainly address them when doing a complete action job. However, dealing with the double-action sear, trigger, and rebound slide will often take care of a lot of friction. Just by focusing on these few areas, you can often make a major difference in the smoothness of a revolver.
One of the great things about this work is that very little equipment is required. All that's needed is some 600-grit abrasive paper, a small wooden dowel, a hand drill, some honing oil, a small hammer, a punch, a bench block, and an India stone. With just a bit of care and patience in addition to these items, the average person can easily make a noticeable difference in the smoothness of his revolver.
After making sure the revolver is unloaded, the first step is to disassemble it. If you're not sure how to do this, pick up one of the many assembly/disassembly manuals currently available. My favorite, and one that I've used in my shop for years, is the NRA Guide to Firearms Assembly, Pistols and Revolvers. This is available from the NRA, gunsmith supply houses such as Brownells and MidwayUSA, or from almost any firearms book dealer.
Once the revolver is disassembled, clean the inside of the frame and each part thoroughly. This will enable you to see the critical surfaces you'll be stoning. Don't forget that gummy oil or built-up fouling can make movement of internal parts much more difficult as well. A clean action is always a smoother action.
The first part to be stoned is the trigger. Keep in mind the area to be stoned is very small. You don't want or need to stone the entire surface of the trigger. That's a waste of time, and it can adversely affect the functioning of the handgun. It's especially important to stay away from the sharp edge of the trigger that engages the sear notch in the hammer. Do not in any way modify, polish, or stone this sharp edge. If you do, you could easily ruin your gun's trigger.
When doing this work, I use a fine-grit 1/2x1/2x6-inch India stone. This "stone" is actually aluminum oxide and is probably the most commonly used stone in gunsmithing. I put a bit of honing oil on the India stone to keep the pores of the stone from becoming clogged with metal particles as it is used. The movement of the stone is from front to back on the trigger. By doing this, any stoning marks will match the direction of movement of the parts. The trigger is clamped in a padded vise with the double-action contact area above and parallel to the top of the vise jaws. As I stone the trigger, I'm careful to keep this area flat and even. Some find it easier to secure the stone and move the trigger over the stone.
The top rear edge of the trigger is slightly rounded. You'll want to maintain this radius, but don't allow the stone to touch the sharp edge at the bottom of the rear of the trigger that engages the sear notch in the hammer. Also, don't make the mistake of stoning too much. Do just enough to remove any machine marks or roughness. As soon as you do that, stop.
Next, the double-action sear is removed from the hammer. The only part of the sear--which may vary in shape depending upon
the model--to be stoned is the end where it engages the top of the trigger. This part of the sear should be just as smooth as the matching surface on the trigger.
The rebound slide is next. The only areas to be stoned are the bottom and back where it contacts the inside of the frame. There is no need to do anything with the top of the rebound slide or the highly polished surface of the side exposed when the sideplate is removed. Again, the India stone and some honing oil are all that are needed. As with the double-action sear and the trigger, the stone should always move in the same direction as the movement of the part.
The hole inside the rebound slide is sometimes rough, and this hinders the movement of the rebound spring. I use a small wood dowel, some 600-grit abrasive paper, and honing oil to polish the inside of this hole. The dowel, which I slot to take the abrasive paper, can be chucked in an electric hand drill. A bit of honing oil is applied to the inside of the rebound slide, and then the dowel and abrasive paper are inserted. A few passes with the hand drill quickly polishes the inside of the hole.
Don't forget to use the stone to polish the inside of the frame where the rebound slide is seated. A few strokes are generally all that it takes. Again, make sure the direction of the strokes with the stone corresponds to the direction of movement of the rebound slide. When you finish, be sure to carefully clean the inside of the frame with a solvent to remove all traces of abrasive and metal particles.
Once this work has been completed, oil and reassemble the revolver. You should find the double-action cycling is significantly smoother. Of course, you can do a lot more to the mechanism. I haven't even touched upon the cylinder assembly and how it affects cycling, but these are good first steps and should make your Smith & Wesson revolver easier and more comfortable to shoot.
Until next time, good luck and good gunsmithing!