Changing main & rebound springs on Model 640 Pro Series

[HLC]

I've fired/dry fired my Model 640 Pro Series over a 1,000 times. The trigger is heavy, but not unbearable, considering how I shoot, which I discuss later. It exceeds the 12 lb. max of my Lyman gauge, before the trigger is even close to breaking - but it is smooth. I have been thinking of replacing the main spring and maybe the rebound spring. I have reviewed every forum and online article that I can find on changing the springs on J-frames. My take away is that most writers seem happy with the Wilson, Wolff and Apex main springs. Several writers do not like the Apex rebound spring because the trigger reset is slower and some call it “lazy." Some said they reinstalled the original rebound spring and were happier with it. Since I am more interested in a quick trigger reset and rapid follow-up shots, I’m inclined to opt for the Wilson or Wolff #15 rebound spring, or keep the factory spring, and change the main spring to a #8 Wilson or Wolff and forego the more expensive Apex kit and the included firing pin and spring. From what I have seen so far, no one who has made a spring change on a 442, 642, 36, 60 or any .38 Special J-frame has had any problems with a failure to fire when the factory firing pin was retained, when using one of the three brands of main springs I have mentioned. However, I’m curious if anyone has made a main spring swap on a 640, or other .357 J-frame, without changing the firing pin, and experienced any failures to fire with .357 loads.

Another question I have is whether or not a spring change will make any noticeable difference or work against me, considering how I usually shoot DA revolvers. From all the articles and forum posts I have read on J-frame spring kits, I cannot tell if the shooters squeeze the trigger using a technique I was taught that tends to ameliorate to some degree a long and heavy trigger pull.

I was trained to stage the trigger on a DA revolver by squeezing it until the tip of my trigger finger is touching the edge of the frame at the rear of the trigger guard. (I can’t use this technique with my 629, because it’s too large.) If you position the "power crease" of your trigger finger correctly, you can rapidly squeeze the trigger and stop as your finger tip touches the frame. The cylinder is fully locked up and the hammer is just ready to break at this point. It then takes a split second to align the sights and then with a slight squeeze of the trigger the hammer drops. After firing, I can squeeze the trigger rapidly and hold it staged (with my finger on the frame) while the sights come back on target and then instantly fire my next shoot with a slight squeeze of the trigger. I don't have to struggle with sight alignment while simultaneously struggling with a long and heavy DA trigger. Rather than concentrate on "squeezing the trigger" to shoot, I concentrate on "touching the frame" with my finger tip.

I shoot my 640 this way. When squeezing the trigger quickly, its weight is not as noticeable as when squeezing slowly. It helps me to have some resistance to void squeezing completely through the trigger as my finger touches the frame, before I am back on target. Has anyone who shoots his or her J-frame using this technique found that changing the main and rebound springs has improved their shooting?

 

[Pef]

I've used the Wolf springs.

I have rebound springs in 11, 12, 13, 14 and 15 pounds. Depending the the gun, I will swap rebound springs until I have a positive reset. On a couple of j-frames that were either very smooth to start or that I have polished (especially the extractor star that is rubbed by the hand during rebound), and I can use an 11 or 12 pound spring for positive reset. Some of my other j frames require 13 or 14 pound springs. Depends on the gun and tolerances, I suppose.

I now also swap the mainspring down to the wolf 8 pounder and I have had positive ignition for thousands of rounds.

I cannot comment on the staging, but I can say that shooting with the wolf springs is very much preferred by me. You will notice a difference at first, and you may be impressed by how much "lighter" the trigger is. Most of my J-frames now have pulls between 9 and 10 pounds.

And this tool makes it easy: Gunsmither Smithmaster Rebound Tool S&W Revolvers

 

[HEADKNOCKER]

A lot of rebound slides need to be drawn across a fine india stone a few strokes to just square them up & make them smooth..
The hammer strut can also take a few passes over the stone to help smooth it up though on the newer smiths the stop is plastic & really makes little to no difference..
I often polish the outside of the rebound spring to make it smoother as well..
I never had much luck with the most lightweight rebound springs, They just don't have enough force to reset fast & can tie the action up as the trigger isn't returning forward enough or fast enough for self defence work..
If you do use the light weight hammer spring be sure test it with your carry ammo of choice at least 50 rounds to assure you get 100% ignition.
Staging the trigger as described for target work is really teaching yourself bad muscle memory, For a smooth clean DAO trigger you should pull the trigger in one smooth action to the rear..

The rebound spring tool I have is like this one--> Wheeler Engineering Screwdriver Bit S&W Rebound Slide Spring
I use a #1 phillips to reinstall BTW..
Also a lightweight oil = Remoil on all the moving parts will make things a whole lot better..

I don't mean to tell anyone how to shoot but the Centennial J Frames are tough to master the trigger on, Takes a lot of trigger /range time..

Good Luck & Stay Safe Out There!!
Gary/Hk

 

[Pef]

OP, this thread will better explain the polishing points on the ratchet (it's addressed in question 2 and the first reply): http://smith-wessonforum.com/s-w-smithing/409454-question-about-j-frame-cylinder-stars.html



In addition to polishing the rebound slide, other places that may help improve the *rebound* is where the trigger engage the cylinder stop *on the return* and the ratchet return surfaces (shown at the 3:00 position).

But only do this if you have patience and are handy with tinkering. Last thing you want to do is ruin your 640 Pro!

Good luck.

 

[gnystrom]

I have a handful of J-frames and fully agree that they need stoning of many internal parts to help with the smoothness of trigger pull. This includes my 640 Pro Series. Dry fire all want. but a few minutes with a hard Arkansas stone will generally provide a better end result.

All have used the Wolff kit in all my J-frames. For me, the best feeling combination is the Wolff 8# hammer spring and the 14# rebound spring.
I handload using range pickup brass and any brand of primer that happens to be on the shelf.
YMMV

 

[HLC]

A lot of rebound slides need to be drawn across a fine india stone a few strokes to just square them up & make them smooth..

I never had much luck with the most lightweight rebound springs, They just don't have enough force to reset fast & can tie the action up as the trigger isn't returning forward enough or fast enough for self defence work..

Staging the trigger as described for target work is really teaching yourself bad muscle memory, For a smooth clean DAO trigger you should pull the trigger in one smooth action to the rear..
I don't mean to tell anyone how to shoot but the Centennial J Frames are tough to master the trigger on, Takes a lot of trigger /range time..]


In another post it was also recommended to polish the rebound slide. I assumed as a Pro Series model, this was done, but I intend to confirm this. I understand that this can affect how strong of a rebound spring is necessary for quick and reliable reset.

Whatever I do, I won't feel confident with it without first shooting at least a few hundred rounds with no malfunctions of any sort.

As for my staging the trigger, I was taught by L.A. County Sheriff's Department to shoot DA revolvers that way. Before switching to the Beretta 92F in 1990, LASD issued the Model 15 revolver. Department policy prohibited shooting revolvers (duty weapon, backup gun or off-duty gun) SA. LASD taught thousands of deputies to shoot this way. Once I mastered it, I consistently shot Distinguished Expert on a 25-yard range. It's much faster and I think nearly as accurate, if not as accurate, as SA.

As for experience with the 640, my backup/off-duty gun was a Centennial 640. To carry it I had to qualify on the same 25-yard range and combat courses as with my duty weapon. This included a 20-second cycle shooting 5 shots, reloading with a speedy loader, and then shooting another 5 shoots. I could not shoot it as accurately as my Model 15 or Beretta, with which I shot 295's and 296's, but I shot consistently in the mid 270's, and a qualifying score was 210 out of 300.

My current 640 has a heavier trigger. I know my older 640 had a 10 lb. trigger, but due to better sights, I shoot the Pro Series more accurately. Using this technique I can shoot vitamin bottles from 6 yards and in 5 seconds can shoot a 5-shot group at 4 yards that makes one hole not much bigger than a quarter. However, if I can improve on this with new springs, without compromising reliability, then I thought I'd give it a try.

To clarify how I shoot, I don't need to align the sights until my trigger finger touches the frame at which point I stop squeezing the trigger momentarily. At this point, it's similar to having "cocked" the hammer to shoot SA, and your finger tip against the frame allows you to hold the trigger at this point without further movement. Then after aligning the sights, its a steady squeeze, like shooting SA. Give it a shot (no pun intended). To be fair, dry fire a few hundred times and then shoot 50 rounds at the range.

 

[HLC]

I handload using range pickup brass and any brand of primer that happens to be on the shelf.
YMMV

Have you had any ignition failures with .357 handloads or factory loads?

 

[Hapworth]

In another post it was also recommended to polish the rebound slide. I assumed as a Pro Series model, this was done, but I intend to confirm this...

The "Pro" series revolvers don't get any special action tuning.

As for my staging the trigger...

This technique is effective for improving accuracy in non-stress scenarios and increasing the likelihood of a negligent discharge in a serious situation. Too much adrenaline for fine feathering of a trigger. Are you using it in force-on-force training?

 

[HLC]

The "Pro" series revolvers don't get any special action tuning.

This technique is effective for improving accuracy in non-stress scenarios and increasing the likelihood of a negligent discharge in a serious situation. Too much adrenaline for fine feathering of a trigger. Are you using it in force-on-force training?

Customer Service at S&W has told me that the Performance Center does polish the internal parts, but they can't tell me what was polished and won't let me speak to anyone in the PC. However, you and a few others have told me that ain't so. I'm going to assume you are correct, until an inspection proves otherwise.

As for staging the trigger, that's how the Sheriff's Department taught DA revolvers to be shot in all scenarios. I wouldn't be pulling the trigger, unless I intended to shoot and during the initial squeeze, I would still have my gun pointed at the target. You are right about adrenaline flowing, which is why I asked the initial question has anyone who shoots with this technique changed their springs. I was concerned that lightening the trigger might lead to a bit of "over travel" and cause me to prematurely squeeze past the staging point. Thanks for your input.

 

[tomcatt51]

As for staging the trigger, that's how the Sheriff's Department taught DA revolvers to be shot in all scenarios.

Over the years what LE has "taught" has changed regularly. Usually from one bad technique to another.

 

[gnystrom]

Have you had any ignition failures with .357 handloads or factory loads?

Never, and that includes models 340PD, 640, 640 Pro Series, 60 Pro Series, and a 60" 38 sp. All with a wide variety of primers and powder combinations from very weak to full house .357 mag handloads as well as factory ammo.
As a RSO I see a lot of fully loaded rounds during the normal daily sweep up of brass. We sort and pull the loaded rounds to try in our guns. It is not uncommon for me to load five different rounds, both .357 and 38sp. in the same cylinder and fire away.

Ignition has not been an issue for me.