Can a lighter rebound spring contribute to light strikes?

[jeffrey]

I put a new lighter Wolff mainspring in my 686-5P, together with a 14 lb. rebound spring. Never had a light strike before with this gun, but I'm now experiencing them with WWB .38 Spec. I'm hoping that I can blame the new rebound spring and not the new mainspring because I shoot the gun a whole lot better with the new lighter springs.

From what I can tell of how a revolver works, it looks like a lighter rebound spring would have some influence (but maybe not alot) on trigger pull, but it's not clear to me that it would have any influence on the weight of the hammer strike. I hope that someone more mechanically inclined will be able to set me straight on this.

 

[tomcatt51]

Rebound spring does not affect hammer fall or lite strikes. Sometimes the Wolff reduced power mainsprings require a slightly longer strain screw for good igniton with hard primers. Winchester primers are hard.

Prevously posted: "An easy way to check is to get an 8-32 set screw (socket style are best they're grade 8). Put it in instead of the stock strain screw and you can adjust your mainspring tension. No screw head to limit how far you can screw it in. Easy way to test. I use them instead of the stock strain screws, notch the socket end slightly for reference (so you can put it back together the same way) and put a drop of 290 Loctite on to hold them in place. A length between 3/8" to 1/2" works depending on your mainspring and grip frame. They also fix the "misfire problem" some people have with the Wolff reduced power mainsprings which isn't a spring problem, just a (too short) strain screw problem."

Some diasgree and insist you have to use a stock (OEM) strain screw.

 

[38-44HD45]

What Tomcat said.

I've found that there is a wide range of "what works and what doesn't" as regards mainsprings and strain screws on Smiths, especially on the later ones with frame-mounted firing pins. I've also found a fairly wide variation in the length of strain screws in later production Smiths. Therefore, the conventional gunsmith wisdom that a factory stock strain screw, fully tightened, will prevent light strikes ain't necessarily so, just as it is not necessarily true that a shorter screw or one that is backed out a bit will cause light strikes. For whatever reason, I've lately encountered more ammo with overly hard primers than ever before, in several different brands, seeing revolvers with heavy firing pin strike failing to ignite them. But, the rebound slide spring will not affect strike energy.

 

[tomcatt51]

If you want to really lighten your DA pull, Federal primers are still a must.

 

[38-44HD45]

Originally posted by tomcatt51:
If you want to really lighten your DA pull, Federal primers are still a must.

+1, no doubt.

 

[bountyhunter]

Originally posted by jeffrey:

it's not clear to me that it would have any influence on the weight of the hammer strike.

Rebound slide spring has no effect on hammer strike force. That is strictly the mainspring.

The RB spring does have a measurable effect on DA trigger pull.

 

[jeffrey]

I just compared the length of the strain screw of my 686-5 with that of my 66-5 (both guns have a frame-mounted firing pin) and they are the same. I have the same reduced power mainsprings in these guns, but I have had no problems with light strikes in the 66-5.

Is it just that all these guns are a bit different?

Is there a way of getting a slightly longer strain screw for the 686?

I have never had a problem like this with my (many) older Smiths. These two guns are the only ones I own that have the frame-mounted firing pins and other new-fangled MIM parts.

 

[magnum12pm]

Its not likely you will get reliable ignition with the reduced power main spring unless you use Federal primered ammo. You did not say which spring weight you used in the rebound. I have a 686 with the reduced power main spring and 16lb. rebound spring. The double action pull weight is 7 pounds 6 oz. I see no reason to attempt to go any lower. I reload with federal primers for it and never failed to ignite a primer. I was really trying for around 8 pounds but decided to settle for what I had. If you put a longer strain screw in doesn't that defeat the purpose of the reduced power main spring guys? My bad you did give the rebound spring weight

I don't see any reason to go below 7 pound pull, however to each his own.

 

[38-44HD45]

Originally posted by jeffrey:

Is it just that all these guns are a bit different?

Yes, they are. There will be differences in headspace, end shake, firing pin length, and friction between various parts, all of which can act together to create tolerance stacking and result in misfires. You might measure the headspace of both your revolvers. I'd wager that you'll find that the headspace on the 686 is a thousandth or so more than the 66 has. Cylinder and Slide Shop makes an extra-length firing pin that would solve the problem, but you'll have to remember not to dry fire your gun if you install one, since the firing pin will eventually break if you do. I have their firing pins in both my 3" 681+PC guns, and they work well with even WW and CCI primers, with DA pulls of about 7 lbs on each gun.

 

[MR.G]

Rebound springs won't cause light strikes. I use the 11lb Wolf rebound in all of my S&W revolvers without any problems. For them to work well, the insides usually need to be polished with 600 grit and a stone . In the newer guns, with the frame mounted firing pins, I only use the Wolf standard pressure Power Rib mainsprings. The strain screw does not set well against the rib in the Wolf spring, and will sometimes cause it to move off center. The strain screw can be slightly rounded off at the end so that it will seat into the rib of the Wolf spring. The strain screw with a rounded end, and a standard power spring seem to work well.

 

[magnum12pm]

MrG: I was wondering if your trigger resets fast enough with the 11 lb. rebound. I have tried 13 & 14 lb. springs and found they will not reset as fast as I can pull the trigger. In other words my finger out runs the trigger, when attempting to shoot fast.

Originally posted by MR.G:
Rebound springs won't cause light strikes. I use the 11lb Wolf rebound in all of my S&W revolvers without any problems. For them to work well, the insides usually need to be polished with 600 grit and a stone . In the newer guns, with the frame mounted firing pins, I only use the Wolf standard pressure Power Rib mainsprings. The strain screw does not set well against the rib in the Wolf spring, and will sometimes cause it to move off center. The strain screw can be slightly rounded off at the end so that it will seat into the rib of the Wolf spring. The strain screw with a rounded end, and a standard power spring seem to work well.

 

[MR.G]

MrG: I was wondering if your trigger resets fast enough with the 11 lb. rebound. I have tried 13 & 14 lb. springs and found they will not reset as fast as I can pull the trigger. In other words my finger out runs the trigger, when attempting to shoot fast.

I have found that an 11lb rebound spring will work fine, and make a real nice trigger, if everything inside is polished and lubed. Any excess friction and the trigger will not rebound properly. If the trigger is not rebounding fast enough, you're not done polishing.

 

[Fastbolt]

I was wondering if your trigger resets fast enough with the 11 lb. rebound. I have tried 13 & 14 lb. springs and found they will not reset as fast as I can pull the trigger. In other words my finger out runs the trigger, when attempting to shoot fast.

Not an uncommon observation.

When I first started experimenting with a 642 (trying to improve the gun more quickly than the user

) I tried the standard kit of reduced power rebound slide springs. Even with a 'deburred' rebound slide the 11 lb spring wouldn't consistently allow trigger recovery in my 642. The next higher rated springs did to varying degree, and I finally settled on the heaviest of them for good trigger recovery in my 642, which was an off-duty weapon. (This modification was done and approved by the head armorer of my agency at the time, FWIW, so it wasn't something I just decided to do on my own.)

It wasn't that many months later while training that I noticed my trigger finger was now commonly out-running the trigger recovery during various drills and qualification courses-of-fire. I replaced the lighter rebound slide spring with the factory one and got rid of the lighter springs. I noticed an immediate improvement in my trigger recovery ... and kicked myself silently for not having focused on improving me right away and looking for an easy improvement to the weapon.

Even "if everything inside is polished and lubed" you can't always predict when the circumstances in which the gun may be used for defensive purpose may result in the introduction of dirt, grit, moisture, oxidation or even the accumulation of excessive fouling into the gun. A lighter rebound slide spring may not have the strength to function normally as intended under unexpected adverse conditions and circumstances, or even normal conditions at some point.

Now, if it's just a dedicated range enjoyment, sporting, competition and target revolver then there may be different considerations for someone. Gunsmiths make a living doing such things for such folks, you know.

Here's something else to consider, though.

In a S&W revolver armorer class the instructor emphasized that the primary safety of the 3 'safeties' of a S&W revolver is the rebound slide.

For example, if a revolver cocked in single action is dropped and the hammer falls, the rebound slide must 'beat the hammer home' so the raised opposing surfaces of the rebound slide and hammer ... (the rebound seat on the bottom of the hammer and the hammer seat on the top of the rebound slide) ... are in the proper position relative to each other to prevent the firing pin from hitting the primer and the gun discharging. The hammer blocks in revolvers with 'external hammers' index off the rebound slide, too.

A lightened rebound slide spring impedes the speed of the rebound slide returning to its intended forward position where it can act as the primary safety.

Then there's the consideration that some of the fastest revolver shooters throughout the years also preferred the fastest trigger recovery they could obtain ... meaning a strong rebound spring ... (without having a 'monster' rebound slide spring bend or break the frame stud holding the spring in place, of course

).


In the matter light strikes I'd be more likely to suspect either the lighter main spring or a primer sensitivity issue, or a combination of both.

I'm not an expert or a gunsmith, though. Just a guy who's sat through some armorer classes here and there ...

 

[MR.G]

Even "if everything inside is polished and lubed" you can't always predict when the circumstances in which the gun may be used for defensive purpose may result in the introduction of dirt, grit, moisture, oxidation or even the accumulation of excessive fouling into the gun. A lighter rebound slide spring may not have the strength to function normally as intended under unexpected adverse conditions and circumstances, or even normal conditions at some point.

Good point. Accumulation of durt or fouling in the gun can cause a trigger to return slower with a weaker spring. My sideplates are removed and internals cleaned after every range session.