Replacing the cylinder stop spring

[Mike_Fontenot]

With side plate off, wedge trigger back a bit with a an eraser to take tension off of the cyl bolt. Don't remove the bolt. With a dental pick, pull one end or the other of the spring out, the bolt or the pocket in the frame. Replace spring by reversing that maneuver.

WOW ... that is VERY helpful information! I would never have suspected that there is enough of a gap between the rear of the cylinder stop and the hole in the frame to get the spring out with the cylinder stop fully seated down against the frame. Thanks!

 

[Mike_Fontenot]

[...]

Thanks very much for all that useful information. When I get the stiffer spring, I'm going to first try Hondo44's method of replacing the cylinder stop spring without removing or partially elevating even the cylinder stop. If I'm successful with that method, I'll be done (at least for now). If I'm unsuccessful, I'll go with the disassembly you've described. I've watched a bunch of YouTube videos, and together with your really good verbal description, I'm not feeling quite so intimidated by it now. I also have the Jerry Kuhnhausen shop manual, but it leaves a lot to be desired.

 

[WR Moore]

I haven't read all the posts, but one very important item is to make sure that the spring is straight with respect to the hole in the cylinder stop once installed. Otherwise, it may bind and cause you problems.

Now, if your firearm is indeed "backspacing", the problem generally isn't just the cylinder stop. I did a whole bunch of N frames back in the day and they generally had excessive endplay and yokes that weren't properly aligned with the frame.

If you confirm the issue does in fact exist, I'd suggest making use of the factory warranty.

 

[Mike_Fontenot]

[...]
If you confirm the issue does in fact exist, I'd suggest making use of the factory warranty.

Thanks for those tips.

There are several reasons why I didn't want to send it back to the factory. First of all, they wouldn't put in a stiffer cylinder stop spring. Secondly, they wouldn't test it with Underwood 240gr's. Thirdly, I'd have to first take out the lighter mainspring and rebound spring that I put in to get the light trigger I wanted ... I found out the hard way, when I sent my 686 back under warranty, that they remove the light springs and put it back to a stock trigger.

But if my stiffer cylinder stop spring doesn't solve the problem, I'll need to bite the bullet and remove my light springs, and send it back. I REALLY hope I don't have to do that.

 

[armorer951]

I also have the Jerry Kuhnhausen shop manual, but it leaves a lot to be desired.

In what way? I've been referring his series of books for 20+ years and still find them useful and informative.

 

[Protocall_Design]

When removing or replacing the cylinder stop spring, I would just take out the rebound slide, trigger and cylinder stop to avoid possible damage to the spring. It only adds 30 seconds to a minute to the whole operation.

 

[Mike_Fontenot]

I can send a short video if you need one....or just Google it.

I HAVE found a couple of pretty good videos via googling. But I'd also like to see yours.

 

[Mike_Fontenot]

[...]
With side plate off, wedge trigger back a bit with a an eraser to take tension off of the cyl bolt.
[...]

About how far back does the trigger need to be? Does the part of the trigger that sticks into the slot of the cylinder stop (when the trigger is all the way forward) need to be out of that slot? I.e., does the the trigger need to be pulled back only far enough so that the cylinder stop has snapped up into the frame?

 

[Mike_Fontenot]

About how far back does the trigger need to be? Does the part of the trigger that sticks into the slot of the cylinder stop (when the trigger is all the way forward) need to be out of that slot? I.e., does the the trigger need to be pulled back only far enough so that the cylinder stop has snapped up into the frame?

It's looking to me like the distance between the lower rear of the cylinder stop and the opening of the hole in the frame is maximum whenever the ball of cylinder stop is all the way up in the frame. And this occurs both when the trigger is fully released, and when the trigger is pulled far enough for the trigger to flick down out of the cylinder stop slot. If so, I think I can just leave the trigger and hammer in their rest positions. That should give me the most room to extract and remove the spring, and insert the new spring.

 

[armorer951]

You are correct, but in doing it this way, you will likely destroy the old spring and inevitably risk damaging the new spring. It would be better to remove the current stop and spring, and install the new spring in the cavity at the rear of the stop, then re-install.

 

[acl864]

After reading the original posters explanation of the issue. I'm wondering if the recoil isn't causing a 'short stroke" on the trigger. That would explain the functioning issues and I've seen that happen before on DA guns with hyper recoil.

 

[Hondo44]

It's looking to me like the distance between the lower rear of the cylinder stop and the opening of the hole in the frame is maximum whenever the ball of cylinder stop is all the way up in the frame. And this occurs both when the trigger is fully released, and when the trigger is pulled far enough for the trigger to flick down out of the cylinder stop slot. If so, I think I can just leave the trigger and hammer in their rest positions. That should give me the most room to extract and remove the spring, and insert the new spring.

You're exactly right.

 

[Mike_Fontenot]

I just got back from the range (and I haven't done the spring replacement yet), and it DID show that the problem IS correlated with the power of the round, although not to the degree that I had expected. The full-spec Underwood 240gr had the problem on the very first shot. Then, I shot two sets of 5 rounds of Black Hills (about mid-range .44mag), and expected no failures, but got 1 failure out of the 10. Next, I shot 3 sets of 5 rounds of S&B (about at the bottom of .44mag), and got 1 failure out of the 15. Finally, I shot 4 sets of 5 rounds of Georgia Arms (really about mid-way between the bottom of true .44mag and the top of the .44 Special+P range). I got no failures out of the 20.

After Thanksgiving, I'll put in the stiffer spring and see if I still get any failures with the UW 240gr ammo. If I do, that will tell me that there is some other problem. If not, I'll be done.

 

[Mike_Fontenot]

After reading the original posters explanation of the issue. I'm wondering if the recoil isn't causing a 'short stroke" on the trigger. That would explain the functioning issues and I've seen that happen before on DA guns with hyper recoil.

Thanks for that tip. If the problem doesn't go away after I put in the stiffer cylinder stop spring, that may point to the possible cause you've brought up, or maybe to something else. I HAVE previously put in the lightest possible trigger rebound spring, in order to get the 2-1/2 lb SA trigger pull I wanted. I also put in a lighter mainspring, just heavy enough to prevent any light strikes. The DA pull is still not extremely light ... probably about 9 lbs.

I've done the same SA trigger-pull modifications on my 686 .357mag, in order to get the same trigger pull as on my 69 .44mag. I've shot that gun a lot with full power Underwood 158gr ammo, without this problem currently happening. But a while back, I did get an even more drastic failure on that gun, where the cylinder stop quit working at all, and just left the cylinder to rotate constantly, even after multiple cocks of the hammer. I sent it to S&W, and they said they replaced the trigger stud. It's been shooting fine since.

 

[Hondo44]

Push in on the frame mounted firing pin from the rear to inspect the tip. Does it look like it extends long enough and is it properly shaped?

 

[Mike_Fontenot]

I'm wondering if the recoil isn't causing a 'short stroke" on the trigger. That would explain the functioning issues and I've seen that happen before on DA guns with hyper recoil.

I think there is evidence that "short stroking" of the trigger can't be the cause of my problem. When the cylinder rotates after the shot, the firing pin is leaving a trail scratched on the back of the brass. The firing pin doesn't retract until the trigger is released. And after the firing pin retracts, it doesn't again protrude until the hammer is fully cocked, released, and hitting the firing pin. So the rotating of the cylinder is happening BEFORE the trigger is released after the shot.

 

[Mike_Fontenot]

Push in on the frame mounted firing pin from the rear to inspect the tip. Does it look like it extends long enough and is it properly shaped?

Yeah, it looks fine.

 

[WR Moore]

After noting that your problem only exists with a specific boutique load, I'd strongly suggest you simply don't use that ammunition any more.

I've never used Underwood, and only recently heard of them and have nothing personally against them, but I long ago watched several firearms destroyed by loads from various boutique ammo makers that promised exceptional velocities at SAAMI pressures. They were half right. A few foot seconds isn't worth the risk.

 

[Fostereast]

Really silly question but... have you measured the trigger pull? It sounds like you have modified the hammer and trigger springs. If the springs are lighter it's possible the primers used in one type of ammo work and the primers in another type are too hard to fire. As an example, in general any competitive shooter that reloads, tends to reduce the trigger pull and then use Federal primers, because other primers tend not to fire.

It sounds like you have a good handle on the problem, but if the trigger pull is reduced, certain brands of primers become unreliable.

 

[Protocall_Design]

It may be that the recoil is causing the cylinder stop to bounce down during recoil, unlocking the cylinder and allowing it to rotate. If that's the case, a heavier spring may help, or it may still not be strong enough. On some heavy recoil N frames, that was happening as well as the bolt going forward and allowing the cylinder to go sideways. They have since implemented remedies for that, I don't know if the 69 has the same upgrade.