OP
Mike_Fontenot
Member
The SA trigger pull is about 2-1/2 lbs. But the DA pull is about 9 lbs, and I've never had any light strikes with any ammo.
Replacing the cylinder stop spring
- Thread starter Mike_Fontenot
- Start date
The SA trigger pull is about 2-1/2 lbs. But the DA pull is about 9 lbs, and I've never had any light strikes with any ammo.
OP
Mike_Fontenot
Member
Yeah, that was my diagnosis. I'll know pretty soon if the stiffer spring from Wolff solves the problem.
I've never had the problem of the cylinder bolt unlocking, and allowing the cylinder to swing out of the frame.
OP
Mike_Fontenot
Member
I had some unexpected time today to try to do the spring change in my 69. I initially tried to do it without taking any parts out (other than the spring), but had trouble trying to get the old spring out, even though I wasn't planning on saving it, and was willing to treat it pretty roughly. I didn't have a curved dental pick ... just a couple of pottery tools that my wife loaned me, that were small straight needles mounted in wooded handles, and I had numerous very small screw drivers. I was afraid that even if I was able to get the new spring in (a BIG if), it might well get damaged in the process. So I decided to remove the hammer, rebound slide, and trigger, using several YouTube videos as guidance. I didn't have any problems, but I took it very slow. The hardest part, by far, was replacing the spring in the cylinder stop ... it was much harder for me than for the guys in the videos ... maybe because my spring is stiffer and harder to manage. But I DID finally get it in, and it appeared to work OK. And the reassembly of the other parts went fine. Dry firing seems normal in all respects. I may be able to test fire it with the Underwood 240gr ammo Friday, or perhaps Monday or Tuesday, and see if the problem is gone or not. I SURE hope it's gone.
I was surprised that there were several things about my gun that were different from the older S&W revolvers in the videos I used (they all had the hammers with the attached firing pin). For example, the little safety part that slides in a vertical channel in the frame underneath the rebound slide (I don't remember what it does ... maybe interacts with the cylinder release mechanism somehow(?)) isn't there at all. And the underside of the side plate is quite different ... the narrow long slot that the hammer safety fits into is no longer there.
I was surprised that there were several things about my gun that were different from the older S&W revolvers in the videos I used (they all had the hammers with the attached firing pin). For example, the little safety part that slides in a vertical channel in the frame underneath the rebound slide (I don't remember what it does ... maybe interacts with the cylinder release mechanism somehow(?)) isn't there at all. And the underside of the side plate is quite different ... the narrow long slot that the hammer safety fits into is no longer there.
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Protocall_Design
Vendor
The safety part that slides in the vertical channel is one of the upgrades to keep the bolt from going forward during recoil. It is operated by an extra long pivot pin on the hand that goes through the trigger and runs in a slot at the base of the bolt block. When the trigger is pulled back, the bolt block rises up, when the trigger is at rest, the bolt block is down so you can open the cylinder. I think they should have done these upgrades on the 69 and 696, but they didn't ask me about it. Nor will they ever.
The sideplate still has a track for the hammer block to run in, but is now made much differently. Originally the slot was made with a slotting (or slitting) saw. Now it's made with an endmill. That eliminates a setup and cutting operation.
The sideplate still has a track for the hammer block to run in, but is now made much differently. Originally the slot was made with a slotting (or slitting) saw. Now it's made with an endmill. That eliminates a setup and cutting operation.
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OP
Mike_Fontenot
Member
Thanks for that info. I just assumed that, since the Model 69's are less than 4 years old, that they had just found another way to get that feature. Do the new 629's have it?
OP
Mike_Fontenot
Member
Range trip report:
The "stiffer" cylinder stop spring seemed to have no effect. I got the same failure rate as with the stock spring. Time to send it back to S&W. Bummer.
The "stiffer" cylinder stop spring seemed to have no effect. I got the same failure rate as with the stock spring. Time to send it back to S&W. Bummer.
Have you tried firing the heavier ammo with the OEM (stock) rebound slide spring installed?
OP
Mike_Fontenot
Member
I MAY have fired a few Underwoods when I first bought the gun (about four years ago), but it probably was with single rounds being loaded into the cylinder, which wouldn't have exposed the problem. And after I got the trigger job from a local gunsmith (I didn't do the spring change on the 69, I just did it on the 686), I also fired some Underwoods, but again, it was with only single rounds loaded in the cylinder). I think the rebound spring that the gunsmith put on is a little lighter than the 11 lb one that I put on the 686 (even though mine was the lightest that Wolff makes), but the SA trigger pulls are close to the same.
Could the light rebound spring provoke the cylinder stop unlocking during recoil that I'm seeing?
That's a very light rebound spring. The OEM spring is approx 16-17 pounds.
I was concerned about the behavior of the trigger during recoil, and whether it (trigger hook) could somehow interact with the point of the cylinder stop during the heavy recoil phase of firing. It may just be the cylinder stop itself rebounding out of the stop slot in the cylinder. The stop is going to want to go forward when the frame pushes back during heavy recoil.....and if the recoil is severe enough, the cyl stop spring will not be able to prevent this.
Not trying to tell you what to do, but this malfunction is an indication that the loads you are using are beyond the ability of the revolver to accomodate. Continued use of the heavier loadings will certainly shorten the life of the gun, and may even be dangerous for you or for bystanders. You might consider going to a slightly lower pressure load that the frame and contents can tolerate.
I was concerned about the behavior of the trigger during recoil, and whether it (trigger hook) could somehow interact with the point of the cylinder stop during the heavy recoil phase of firing. It may just be the cylinder stop itself rebounding out of the stop slot in the cylinder. The stop is going to want to go forward when the frame pushes back during heavy recoil.....and if the recoil is severe enough, the cyl stop spring will not be able to prevent this.
Not trying to tell you what to do, but this malfunction is an indication that the loads you are using are beyond the ability of the revolver to accomodate. Continued use of the heavier loadings will certainly shorten the life of the gun, and may even be dangerous for you or for bystanders. You might consider going to a slightly lower pressure load that the frame and contents can tolerate.
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Fostereast
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Springs
You might try the original springs prior to sending it back.
You might try the original springs prior to sending it back.
BruceM
Member
^^^^^^^^This^^^^^^^^
I understand this may not be something the OP wants to hear but that doesn't change the facts. The problem he is having mirrors those which provided the impetus for the Endurance Package now standard on the M29's and M629's as mentioned previously. Now he insists on using an even heavier load in a substantially lighter gun.
There may be no easy and inexpensive fix for this problem other than dialing back the ammo a tad.
Bruce
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OP
Mike_Fontenot
Member
I just realized that I don't know why the rebound slide moves aft when the hammer is cocked. Jerry Kuhnhausen, in his S&W revolver shop manual (page 12, item 2 under "Operating Sequence and Safety Features"), says "At the same time, the rebound slide moves to the rear, ...". But he doesn't say WHY it moves to the rear. Anyone know?
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The rebound slide moves to the rear because the trigger moves to the rear as it is lifted by the hammer.
If you refer to pages 73, 74 and 75 in the Shop Manual, 5th Edition, you can see how the action moves in SA and in DA. Two different forces at work, one by the hammer (SA), and one by the trigger. (DA)
If you refer to pages 73, 74 and 75 in the Shop Manual, 5th Edition, you can see how the action moves in SA and in DA. Two different forces at work, one by the hammer (SA), and one by the trigger. (DA)
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More soecifically:
When you removed the trigger to install the cyl bolt spring, remember that rod sticking out of the back for the trigger that nests in a pocket in the front end of the rebound slide. That's what literally pushes the slide back whether trigger movement is initiated by the hammer in SA or by the trigger in DA.
When you removed the trigger to install the cyl bolt spring, remember that rod sticking out of the back for the trigger that nests in a pocket in the front end of the rebound slide. That's what literally pushes the slide back whether trigger movement is initiated by the hammer in SA or by the trigger in DA.
OP
Mike_Fontenot
Member
OK ... I understand it now. Where I was going wrong was that I thought the plunger from the trigger pushed on the rear of the rebound spring, but now I realize that it doesn't ... the rear of the rebound spring stays fixed at the rear of the cylindrical channel in the slide. The plunger pushes on the rear of the slide. Makes sense now.
Here are some action drawings that may help as you think about the movement of the action......
AT REST:
DOUBLE ACTION, TRIGGER TO SEAR PICKUP:
DA, TRIGGER, SEAR TO HAMMER EXCHANGE:
DA, HAMMER RELEASE POINT:
SA, COCKED, READY TO FIRE:
SA OR DA, FIRED:
AT REST:
DOUBLE ACTION, TRIGGER TO SEAR PICKUP:
DA, TRIGGER, SEAR TO HAMMER EXCHANGE:
DA, HAMMER RELEASE POINT:
SA, COCKED, READY TO FIRE:
SA OR DA, FIRED:
OP
Mike_Fontenot
Member
Thanks. Those are very useful.
I'd have to agree. In the late 70's I shot metal silhouette with a Mod 29, found the max load in the loading tables was my accuracy load, so one weekend a month I'd hammer the gun with 80 rds of very hot 240 gr shells, plus practice.. Every 6-8 months, I'd find the gun doing exactly what you described, wondering how the heck the fired brass got under the hammer when I pulled the trigger. Long story short, a fine gunsmith, the late Fred Schmidt, looked into my problem and would find the gun had to be retimed and the crane straightened. He was of the opinion that the N frame wasn't quite up to the 44 Mag punishment and that the top strap was stretching under max loads. He installed a ball detent for the crane before that was fashionable, and that helped, but I still had to take it back at least once a year for a tuneup until I sold the gun.
IMHO, if you feed your L-frame gun a steady diet of hot 44 Mag loads, you'll continue to have problems. If you want to shoot bear killers, get a Redhawk.
I think your situation is analogous to the Model 19 and max power .357 loads. It won't blow up the gun, but you'll wear it out before its time.
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OP
Mike_Fontenot
Member
Thanks for that info. If those are a problem with my 69, I wish S&W would figure it out and fix it. Do you remember exactly how the timing was "off"?
On the other hand, if nothing's wrong with my gun, I can live with the problem. The full-strength mainspring prevents the actual malfunction, even though there still is cylinder unlocking and a little bit of cylinder rotation.
