Troubleshooting misfires on S&W 586 L-Comp

Status
Not open for further replies.
W

westernrover

Member
Joined
May 4, 2018
Messages
1,613
I have an L-frame that misfires or fails to ignite primers. I would estimate the rate of misfires to be two or three percent. Yesterday, it misfired more or about three out of fifty. I have another L-frame that has fired thousands of rounds (probably 8000) of the same primers, same brass, same loads without a single misfire. I've been trying to figure out why one works and the other does not.

Strain Screw
In my own efforts, the first thing I did was to check the strain screw was tight. I confirmed it was screwed all the way in. I noticed it was shortened (presumably by the Performance Center before it left the factory as I am the first owner). Later, I would replace it with a full-length strain screw but to no avail.

Factory Service
I sent it to S&W. Unfortunately, they only test-fired it 14 times with no misfires, made a note of this, and that no repair was necessary, and sent it back.

Trigger Weight
I tested the trigger pull weights of the two revolvers. This is a Performance Center-branded revolver that is claimed to have been produced at the factory with an action job. It tested on a Lyman gauge at 9 pounds. My L-frame that is totally reliable has an after-sale action job by the Performance Center and tested at 7 pounds. Unfortunately, it's also the one that the Performance Center gouged the chamber throats of with a machine tool and then refused to fix or replace the cylinder claiming it was within spec. It also has an occasional but rare problem where the sear won't break but exceptionally hard (I thought it was in my head until an instructor firing it at a 4-day class noticed it and said something). In any event, the misfires are not due to weak springs nor is the dependability of the one revolver due to heavy springs.

Spring & Pin Swap
My next step was to swap the mainspring, firing pin, and firing pin spring from the reliable L-frame into the one that misfires. If that combination worked in one L-frame, perhaps it would work in the other. Both revolvers feature what S&W calls "bossed" mainsprings. They look like Wolff Power-Rib mainsprings. According to one article on Revolverguy.com, the Performance Center uses Power Custom ribbed mainsprings. I don't know who makes them but both springs are bossed/ribbed and have the same width and thickness and test very close to the same when I used a spring weight tester. Both revolvers have full-length (unground) strain screws at this point. Upon measuring the firing pins, I found the revolver that misfires had a 0.490" length pin. The dependable revolver had a 0.495" length pin. I also noticed the short pin has a cone-shape tip whereas the longer pin's tip is hemispherical. I was sure to keep the pin and pin springs together as pairs since I don't have a practical means to measure their rates.

pins.jpg
Short 0.490" pin with sharp nose above; below: 0.495" pin with round nose

With the known-good mainspring, firing pin, and firing pin spring combination in the troublesome L-frame, I found that it continued to misfire (three out of fifty yesterday). The other L-frame continued to firing dependably even with the springs and short firing pin -- although I only tested this yesterday and not for the thousands of rounds its previous configuration has been proven with.

Additionally, I tried swapping the mainsprings back again so that I tried both with the longer firing pin. I still got three misfires out of about fifty.

Cylinder & Crane Swap
I had the cylinders out when I was cleaning the two revolvers and I decided to try installing their cylinders in one another. What I found was that the cylinders are swappable, but the crane and cylinder pairs are not. The crane from the troublesome L-frame has a longer cylinder spindle. The cylinder pushes the crane farther forward toward the muzzle and it will hit the frame instead of closing.

The next thing I checked was the headspace and found both within spec. I hadn't ignored this, being an obvious risk factor for misfires. It looked fine and I would check it again more carefully later.

I measured the cylinder windows. The troublesome L-frame has a window of 1.820" and the dependable one is 1.815" from the recoil shield to the frame next to the forcing cone.

Because the frame window on the one revolver is five thou longer, the crane spindle was machined longer also: 1.478" vs. 1.472" The cylinder itself is also 2 thou longer, so the crane and cylinder assemblies are 1.868" vs. 1.860" from the face of the ratchet to the flange of the crane adjacent to the gas ring.

When I load the longer crane and cylinder assembly into the short-window frame, it pushes the crane out far enough from the recoil shield that the crane hits the frame and will not close.

Headspace Check
Well, so what? As long as the headspace is correct and the barrel-to-cylinder gap isn't excessive, I'm not going to fuss about two guns being different by a few thou. I checked the headspace again, more carefully. I found the dependable revolver's headspace was 63 thou. The troublesome's greatest headspace was 65 thou on that one chamber. All this should work fine by a fair margin.

I used a 10X loupe to check for other problems like peening around the breech face or something in the firing pin housing.

good.jpg
Inside the known-good L-frame action; note the polishing performed by the PC

Heavier Mainspring & Extended Firing Pin
I could put a heavier mainspring in this revolver if I could find a heavier one, along with an extended firing pin from Cylinder & Slide for example. I don't really cherish the idea of having a heavy trigger pull on this ~$1400 Performance Center revolver.

Other Fixes?
I don't know what else I could do to fix it. I notice the hammer is different. It has the "teardrop" hammer spur and I can see the hammer is made from an entirely different mold than the stock K&L S&W hammer. I wonder if the geometry if this hammer is somehow different. I suppose I could try swapping it, though I think hammers and triggers should be kept as pairs because of how the sear surfaces are ground or stoned.

bad.jpg
Inside the PC-branded L-frame action that misfires; note the different hammer and trigger

Past, Present & Future of this Gun
I remember when I bought it. My dependable revolver was at the Performance Center getting the chamber throats gouged. They had it for 6 months and I had been expecting it back (because of their estimate) before a 3-day class I was traveling out-of-state for. When I realized it wasn't in fact going to get back to me in time, I rushed to buy this Performance Center gun already cut for moonclips (which I need to keep up with the Glock boys in classes). The very first time I took it out, it misfired. My heart sank because I didn't have time to fix it before the class and I didn't have time to buy a third revolver (none at LGS's so I would have had to order again). I ended up taking it and just misfiring my way through the class -- at least with a double-action revolver all I had to do was pull the trigger again.
 
I dont have a PC gun, and Im only going on whats worked for me with S&W revolvers in the past, where I got them used and people messed with the triggers trying to get them lighter.

What Ive done with them is this, make sure the strain screw is right, replace the mainspring with a full power Wolff, and with that, put a spent primer cup under the strain screw to deal with the rib on the Wolff spring.

Doing that has, so far anyway, always taken care of the issue. It wont make your trigger lighter though, but Im accustomed to and comfortable with factory weight DA triggers, so it doesnt bother me.
 
Since you have already pulled the firing pin, a longer firing pin is where I would start. Also add the fired primer cup under the strain screw. (I prefer Large primers for this trick.) The C&S lengthened firing pin is perfect for the job.

I put enhanced (longer) firing pins in all of my CZ pistols and Glocks with lighter mainsprings, and one in my 7.62x39 AR-15, to improve primer strikes. Since doing this I have not had any light strikes or other misfires involving primer ignition.

These are easy to try and should help with your issues.

Stay safe.
 
UncleEd said:
Moon clips being used or not with misfires?
Click to expand...

Both. I know there's some speculation that omitting the moonclips could result in additional headspace. Clips could reduce headspace if the cylinder was not relieved sufficiently for them or if they were bent. I don't think they add any headspace if the cylinder is sufficiently relieved for the clips such that the rims are still on the edge of the cylinder. In any case, it misfires both with and without moonclips. Generally, I shoot with moonclips. I have about 70 of them from TK Custom and a BMT mooner/de-mooner. I carry moonclips. My reload practice is all based on moonclips. I use moonclips in classes.

I can get the extended pin from TK, Midway or Brownells. Brands are TK, C&S and Apex. At <$20, it would be irrational not to try it before I take a loss on the gun and buy another kilobuck revolver. I just hope I don't start getting damaged primers dragging on the recoil shield or pierced primers. I like features, but I tend to be conservative with mods. It disturbs me that I might have to modify this outside the factory spec just to get it to work. My other L-frame does not need that to work.
 
A test for a Smith and Wesson revolver, model 28, 357mag., may work on other guns also<> Gun empty.
Dryfire gun and hold trigger fully to rear.
Cock hammer with thumb.
Hook a weight around the hammer (for example 3 1/2 LB minimum weight for 357).
The hammer must not move rearward when the gun is lifted.
The hammer should lift 3 1/2 lbs without going into the cocked position.

Your gun has a trigger stop? Should have some over travel.

Has end play been eliminated?

Tried different primers?
 
It looks like the hammers will hold 17 Newtons or about 3.8 pounds hanging from the notch below the hammer face. It's about the same for both. If there is any difference, I cannot measure it accurately enough. These hammers don't have a hammer nose like a Model 28.

My good one has more end play because it's been shot a lot more.
 
Last edited:
When you look at the round under the hammer from the side, is the rim against the cylinder or is it being held away from the cylinder? If something is holding it in the rearward position then it might be able to move forward when the firing pin hits it and that might be enough to cushion the blow and result in a misfire once in awhile.

Check each of the chambers--it might be only one that has the issue.
 
JohnKSa raises the question which I also planned
to ask after wondering about the mooncllips. Have
you tried checking, isolating a particular chamber or
chambers when misfires occur?
 
Send it back to S&W and tell them to fix it. Over the years, Ive had to send two things back to them, and with both, it took three tries to get it right. In both cases, I got a new gun that worked.

They are annoying to deal with, but they do seem to take care of you, eventually.
 
I bought a 66 last winter that would misfire about like you're describing. I took it to an old friend that's a retired gunsmith. He took it apart and worked over the hammer and several other internals with a very fine file. He explained the newer parts sometimes have little burs you can barely feel that will slow down the hammer fall just enough. He also put in a lighter recoil spring. It's a joy to shoot now.
 
I installed the Cylinder & Slide extended firing pin from Brownell's. It's 0.510". I used it with all the other parts in the revolver the original ones that came from the Performance Center. This is a Performance Center revolver that came from there with the internal parts polished by the S&W gunsmith. With this configuration, the gun would not ignite a single primer. So I replaced the strain screw that was ground-down by the PC with a full-length (unground) strain screw tightened all the way. With this strain screw and the extended firing pin and all other parts factory-original, the gun misfired at least 5 or 6 times in 50. I'm done with it. I only have a use for carry guns and I cannot carry this one.
 
That's too bad that you're having trouble like that. I know what that feels like, Does it fire reliably on single action? Not that it should matter but if they're reloads what kind of primer are you using?
 

I noticed these guys had the same problem with the same gun. I appreciate their channel because they review quite a few revolvers and demonstrate double-action shooting with them rather well. I think it's evident from the video that they're not just making the video to gripe about the gun. I don't know what happened with their L-Comp, if S&W fixed it or not.

I use Fiocchi ZP primers -- and that's a hard given. Maybe the gun will fire with Federal, but that is totally irrelevant to me. As mentioned, my 686 fires the very same cartridges with total dependability, so the primers and cartridges are known-good. They also have a very high level of consistency. They are all from new Starline brass and processed with the highest precision equipment. These are not mixed range trash that Bubba cranked out while watching Monday night football and trying to set a new record on his progressive after a few beers. The guys on Berretta9mmUSA were using SIG factory ammo.

I'd like to know what the issue actually is. Since I swapped in known-good springs and pins and headspace checks out, I'm really at a loss for what the cause is. It could be friction between the hammer and frame (it is lubed and should have been polished as part of the Performance Center package), but possibly the hammer (which is from an unusual teardrop metal injection mold) or the frame is warped causing binding -- I don't know and I hate to just speculate when I could be totally off base. What I do know is that S&W refused to fix it, I haven't been able to fix it with parts swaps, and at this point I'm no longer willing to trust it.
 
Send it to a reputable gunsmith with a very concise list of what you have tried that did not work. You are just going to have to pay to play with this one.

ETA. I am with 243, I think there is something out of time and sapping the hammer fall.
But I am not smart enough to find and fix it. See above.
 
Last edited:
The trigger-mounted over-travel stop on S&W Performance Center guns is for single action. The double-action sear breaks well before the trigger stop engages.

The hammer pivot pins are different because the problem 586 PC gun has the hammer with the "teardrop" spur. It's a MIM part but made with a different mold than the standard hammer. Mine shouldn't have excessive wear on it and it would certainly have less wear than the 686 I'm comparing it to. The 586 has maybe three to four thousand rounds through it. The 686 has over 10,000 and a trouble-free record of about 8000 of the ammo I'm using.

I do suspect the hammer could be a cause and that pivot is suspicious. I could swap hammer and trigger pairs (to keep the sear surfaces with their mates) and see if it resolves the problem on the one gun and moves it over to the other. If I did that, I would have to burn some more ammo through this gun and the outcome would either be confirmation the hammer is the cause or it is not the cause. S&W won't replace the hammer. They've claimed it's in spec. I won't replace the hammer because a Power Custom hammer would cost me almost $150 and then I'd have to pay at least that much to have it fit and stoned. If the hammer isn't confirmed the problem, then I'd still be lost and out the ammo I burned.

Besides the extended firing pin, I got a no-go headspace gauge from Brownells. Previously I measured it with an empty case and feeler gauges. No-Go gauges usually have a margin built in so if they block the cylinder closing, the headspace is well within the allowable range. All the chambers on this one look good for headspace.

I also got a precision-ground range rod from Brownells. I got the Match version. I used it and confirmed the timing on this revolver is good on every cylinder. Incidentally, it verified the barrel wasn't crushed when it was threaded into the frame. I found that was a problem on one of my other S&W revolvers.

In any event, this one's going to the store tomorrow with the factory parts. This store test-fires guns before they buy them, so they'll know whether it meets their standards, and if anyone buys it from them, they can shoot Federal primers or take it up with the store or S&W, but I'm cutting my losses.
 
I would be interested in what they offer you for that handgun. I am assuming it was a $1,300 piece new?
 
westernrover said:
In any event, this one's going to the store tomorrow with the factory parts. This store test-fires guns before they buy them, so they'll know whether it meets their standards, and if anyone buys it from them, they can shoot Federal primers or take it up with the store or S&W, but I'm cutting my losses.
Click to expand...

I certainly understand your frustration and admire the amount of time and effort you have put into trying to make the gun right. With the amount of similar issues folks have had with the L-Comp, I have a hard time believing S&W denies there is an issue. Before I passed along a problem gun to someone else, I personally would continue to send it back to S&W until they provided a solution. I could not take it to my LGS without disclosure about the issues and I know that by disclosing the issues, they, being responsible, would probably not take it, and I would not blame them.
 
Two thoughts but probably neither are solutions. First the primers. It is possible that the revolver is within a known spec but the primers are sometimes tougher than what the normal spec calls for. For instance the 686 may strike on the high end of force and never be a problem but the 586 may strike on the low end under normal conditions fine but with the primers you are using just not enough. I have struggled with varying primer issues over the years on what have been known to be Uber reliable revolvers. Second is front end play. Is there just enough movement upon a strike to cushion the primer strike? It doesn’t have to be excessive, just enough. What I am getting at is that it may be more of a combination of issues that put the revolver within specs but close enough to minimum that combined several issues come together and cause the problem. I completely understand the frustration and I am only guessing because you have done more exploration and research than probably 90% of factory or local smiths would. In the vast majority of situations one or two of the issues you remedied would have fixed the problems.
 
Have you considered replacing the ribbed mainspring with an OEM flat spring? Even those aren't entirely consistent; have an assortment in the spring box.
Have a 325 that got a tune/springs by moi, and it promptly started misfiring. Did what the OP did, swapping springs from other M25s. Still misfires; finally put in the thickest of my mainsprings, and the issue went away. Double action is still quite good.
Moon
 
westernrover said:
In any event, this one's going to the store tomorrow with the factory parts. This store test-fires guns before they buy them, so they'll know whether it meets their standards, and if anyone buys it from them, they can shoot Federal primers or take it up with the store or S&W, but I'm cutting my losses.
Click to expand...

I wouldn't do that. I once sold a gun I could not get to shoot, then felt guilty about it until the buyer tracked me down and told me how wonderful it was. He had found the combination I could not. Phew.

halfmoonclip said:
Have you considered replacing the ribbed mainspring with an OEM flat spring
Click to expand...

Right. The problem with that spring is that the strain screw drops into the groove, reducing the preload the same as backing out the screw. I have a couple of them with primer cups under the strain screw to shim them back to the normal position. My next spring engineering will be with the Wilson spring. The one after that might be a Skeeter Skelton "buggy whip."
 
Status
Not open for further replies.

Similar threads

T
  • Locked
Charter Arms Undercover .38 is misfiring--again.
Replies
5
Views
1K
tbeb
T
S
  • Locked
S&W 65 Double Action Misfires...
Replies
10
Views
631
Old Fuff
O
MatthewVanitas
  • Locked
S&W M&P misfiring in DA only, random chambers!
Replies
23
Views
2K
R. W. Simms
R
C
  • Locked
DA misfires
Replies
15
Views
1K
Round Gun Shooter
R
D
  • Locked
S&W 586-7 L Comp.
Replies
1
Views
581
Marshall
M
Back
Top