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Do-It-Yourself Smith & Wesson J-Frame Trigger Job

Readers enjoyed the recent D-I-Y Ruger SP101 trigger job article so much that Brad Miller offered to undertake the same exercise with a Smith & Wesson J-Frame.

Do-It-Yourself Smith & Wesson J-Frame Trigger Job

Smith & Wesson’s J-Frame revolvers are renowned as small, lightweight wheelguns that are ideal for self-defense. They’re currently available in .22 LR, .22 Magnum, .38 Special, and .357 Magnum.

As is common with many revolvers, their out-of-the-box trigger pulls are heavy. Twelve-pound double-action pulls are routine. Many people can handle that with no problem, but not everyone can. Some people have weaker hands or painful medical issues that make 12 pounds too much.

Smith & Wesson offers enhanced trigger pulls on some of its guns, usually through the Performance Center part of the company. My understanding is that those double-action trigger pulls come in at around nine to 10 pounds. That can be a significant improvement for many people and makes the J-Frame a viable choice for them.

Do-It-Yourself Smith & Wesson J-Frame Trigger Job Hammerspring
It’s not difficult to swap out the hammerspring (also called the mainspring, marked #1) and the trigger spring (also called the rebound spring, #2), but it’s not easy, either. Some tuneup kits include a new firing pin and spring (#3).

Gunsmiths can reduce trigger pull. It is often a simple task to swap the springs for weaker versions and—shazam!—a much-improved trigger.

Swapping the springs isn’t difficult, but it’s not easy, either. It involves removing the sideplate and tinkering with the internals, something not everyone is willing to try.

According to Wolff Gunsprings, the weight of J-Frame factory springs is 8.5 pounds for the hammerspring (mainspring) and 18 pounds for the trigger (rebound) spring. Wolff offers hammersprings at 8, 8.5, and 9 pounds. Trigger springs are offered from 11 to 16 pounds, allowing you to tune the action to your preference. Wolff’s J-Frame tuning kit has an 8-pound hammerspring and 13-, 14-, and 15-pound trigger springs.

Reduced-weight hammersprings are mostly meant for centerfire guns. Rimfire revolvers typically have stronger hammersprings to help ensure reliable ignition. For example, some rimfire S&W revolvers have 12-pound factory hammersprings. But they, too, can benefit from lighter trigger springs. If you’re looking to lighten your rimfire’s trigger pull, check with your gunsmith. This article focuses on centerfire J-Frame revolvers.

Wilson Combat also has a J-Frame tuning kit, and it has the same spring weights as Wolff’s kit. M*CARBO offers a J-Frame spring kit with an 8-pound hammerspring and a 13-pound trigger spring. ISMI has a reduced-power spring kit with a 7.5-pound hammerspring and a 19-pound trigger spring. TK Custom and Apex Tactical have kits that include an extended firing pin and firing pin spring along with trigger and hammersprings. The longer firing pin is intended to ensure positive ignition. (The firing pin only fits guns that have frame-mounted firing pins.) TK Custom says its kit reduces a 13-pound factory trigger pull down to nine pounds. Apex Tactical says its kit will reduce trigger pull weight by about 3 pounds. The TK  Custom hammerspring is eight pounds, and the trigger spring is 10 pounds. Apex Tactical says they don’t assign weights to their springs.

Do-It-Yourself Smith & Wesson J-Frame Trigger Job Hammerspring Paperclip
The hammerspring is captured by cocking the hammer and putting a paperclip through the hole in the mainspring stirrup.

For this report, I put a TK Custom kit in a new S&W Model 637 .38 Special revolver. It started with a single-action trigger pull of 3.25 pounds and a double-action trigger pull of 12.25 pounds.

Note: If you’re doing a spring change on an aluminum frame, be extra careful to not put too much force on the rebound (trigger) slide stud. It is a steel pin pressed into an aluminum frame, and the joint is not as strong as a steel frame. Thus, the stud joint could crack/break, requiring a trip to a gunsmith or back to the factory. If you’re uncertain about this task, have a gunsmith install the parts.

Because you might want to change just the hammerspring, I started this exercise by doing that. The resulting single-action pull was reduced to between 2.75 and 3.0 pounds, and the double-action pull was reduced to 9.25 pounds (a full three pounds lighter than the factory trigger pull).

Then I replaced the trigger spring, too. With both TK Custom springs in place, the single-action trigger pull was a mere 2.0 pounds. The double-action trigger pull was reduced to 7.75 pounds. That comes to a 4.5-pound reduction in the double-action trigger pull compared to the company’s claim of a four-pound reduction.

Recommended


Do-It-Yourself Smith and Wesson J-Frame Trigger Job Rebound Slide
A flathead screwdriver works well to lift the end of the rebound slide to release the trigger spring (green). The arrow points to the rebound slide stud that holds the spring in place.

TK Custom’s light-rated 10-pound trigger spring functioned effectively to return the trigger in the Model 637. It returned to place quickly when the trigger was released quickly. It returned the trigger a little sluggishly and stagey when the trigger was released slowly, but it always returned the trigger.

I put another TK Custom spring set in an S&W Model 60 and ended up with the same 2.0-pound single-action pull and 7.75-pound double-action pull. Talk about consistency!

Then I tried another spring combination in the Model 60. Using a Wolff 8-pound hammerspring and a 13-pound trigger spring, the single-action trigger pull was 3.0 pounds, and the double-action pull was 10.0 pounds.

The S&W factory firing pin measured 0.489 inch long. At 0.503 inch, the TK Custom firing pin is a little longer (a gain of 0.014 inch). That should help ignition. The new firing pin spring is reduced power (you can feel the difference when compressing it), so there will be less resistance for the firing pin, which should increase its speed and power a bit, too.

Do-It-Yourself Smith & Wesson J-Frame Trigger Job Trigger Spring
A Philips screwdriver works well to hold the end of the trigger spring while reinstalling it in the rebound slide. Always wear safety glasses when working with anything under spring pressure.

Now let’s talk reliability. The hammerspring has to be strong enough to reliably ignite primers. I tested this with TK Custom’s springs and firing pin combo in the Model 60. I used 50 rounds each of handloads with CCI 500 standard and 550 Magnum Small Pistol primers. I selected CCI primers because in my experience they tend to be the least sensitive of common handgun primers. If they fire reliably, the other brands should, too. All rounds were fired double action. All of the CCI 500 primers fired. I had one misfire with the CCI 550 Magnum primers, but it fired on the second attempt.

Not all 8-pound hammersprings are equal. I replaced TK Custom’s 8-pound hammerspring with Wolff’s 8-pound hammerspring. The double-action pull increased from 7.75 pounds to 8.5 pounds, which should produce a stronger hit on the primer. Ignition reliability with this hammerspring was 100 percent with 50 rounds each of CCI 500 and 550 primers.

Be sure to test your gun thoroughly with your preferred ammo after changing springs to make sure it fires reliably and also that the trigger returns reliably.

Do-It-Yourself Smith & Wesson J-Frame Trigger Job Firing Pin
If your tune-up kit comes with a new firing pin, you may undertake swapping out the factory original. The J-Frame firing pin (black arrow) is held in place by the firing pin retaining pin (white arrow). Tweezers will easily remove the retaining pin.

If you’re concerned about reliable ignition, you could replace just the trigger spring and keep the factory original 8.5-pound hammerspring. I tested this spring arrangement in the Model 60 with TK Custom’s 10-pound trigger return spring. With this configuration, the single-action trigger pull was 2.0 pounds, and the double-action trigger pull was 9.5 pounds. The Model 60’s original trigger pull with the factory spring was 12.0 pounds double action. That’s still quite a reduction in trigger pull weight, yet it retains reliable ignition.

Changing springs is a quick way to reduce the trigger pull on your J-Frame. You can do it yourself or you can have a gunsmith do it. You’ll certainly enjoy the lighter trigger pull, and that will help you shoot more accurately.

If you'd like more on D-I-Y trigger jobs, read "Do-It-Yourself Ruger SP101 Trigger Job," also by Brad Miller.




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