S&W K frame 15 revolver trouble

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ret621

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Hello; I have a 1971 vintage SW 15-3 with a 4" bbl. It is in very good overall condition and does lock up tight when tested with hammer dropped. It works fine in double action with no problems seen. The issue is when attempting to fire single action with the hammer cocked back. The position of the hammer and trigger appear to be normal, but when you attempt to pull the trigger for a smooth single action shot..............both the hammer AND the trigger itself go forward at the same time and it appears the hammer will not strrike the cartridge properly. To repeat, the cocked trigger will snap back forward to rest position, instead of remaining to the rear of the trigger guard as it should. Was wondering if anyone could give me an idea on what could be wrong? Thank You.
 
MY S&W triggers return forward from a SA shot as soon as I let off the 3 lbs.
Are you saying yours snaps forward too hard to hold? If so, you have some sort of mechanical fault.
 
agree on mechanical issue

Thanks for the reply. Yes, the trigger does snap back to the rest position somewhat forcefully, making single action shooting not a real option. I did some more testing tonight and it does look like the hammer mounted firing pin does engage and would strike the cartridge properly every time, but the hammer issue does suggest a mechanical problem. Every once in awhile, the trigger does stay to the rear as it does on my other S&W revolvers. I'm hoping to hear what it could be.
 
(1) The hammer block is either working as it should (it prevents the hammer from going all the way forward if the trigger is forward) or (2) the rebound slide which prevents the hammer from falling all the way forward. These are the symptoms and i don't think are the source of the problem.

Check to see if the mainspring screw is loosened. The mainspring may also have been weakened (either ground down to lessen the tension or bent). Also check the stirrup that attaches the hammer to the mainspring. If the stirrup isn't working right, it can impede the hammer's movement forward.

I also wonder if the pivot pin for the hammer is bent. That would retard its forward movement. The gun could be gummed up and needs cleaning too. Also check if the rebound slide stop pin is bent forward, thus compressing the rebound spring further than it needs to be.
 
In the front face of the hammer there is a little lever, called a "sear." When the hammer falls from the full-cock notch in single action firing the sear, for whatever reason, is impacting the trigger and driving the trigger forward - as you describe.

The solution should be to have it examined by a gunsmith who is qualified to work on S&W revolvers (not all are); or return it to Smith & Wesson's service department.

Do not continue to try to fire it. You are battering some internal parts and damage is likely to occur, and may have already.
 
First thing I would think of is the strain screw is backed out.

If backed out too far the hammer stirrup will hit things inside the gun it shouldn't be hitting.

Try tightening the strain screw in the front of the grip frame fully tight and see if anything changes.

rc
 
Sounds like the double action fly (sear) is sticking and striking the trigger. This could have been replaced by someone who didn't realize that the "sear" must be hand fit by some VERY careful filing. The new part is always long from the factory to allow for fitting. Consult a qualified gunsmith.
 
Thanks to all who answered

I appreciate all who took the time to reply and give some great advice and ideas. What I can get from it all is that there is a problem, and I am NOT a smith....so I will likely find a qualified one to look at it, now that I have an idea of what could be wrong. I did see a FFL dealer, who said that he was a bit of a gunsmith..when he could not identify a S&W 15 as a K frame Smith........... YES....... TRUE!............. .I knew enough to stop right there!
 
Qualified smiths are few and far between. Good luck finding one. Best bet failing that is to send it to the S&W Custom Shop to be refit and have a nice trigger job done at the same time.
 
Old Fuff is correct, and yes, that problem almost always results when someone has tried to lighten the single action trigger pull and gotten it too light. The repair may require a new trigger, a new hammer, or both. Each part would cost around $50, plus whatever a gunsmith would charge. You might call S&W; they will likely charge you (not really warranty work), but the job would be done right.

Jim
 
The gun is being operated in the single-action mode. Since the gun is already cocked, the single action bevel of the trigger is past the point where it engages the hammer mounted sear. I doubt if the double action sear is responsible for the problem described.

As for factory fitting the sear long, S&W fits the sear at the factory. It should work right out of the box. Leaving it long means S&W will have to pay some warranty station to adjust it.

I still think it's the stirrup or the mainspring that is at fault. I wonder if the bolt is bent such that it is impeding the hammer's forward rotation? How does the cylinder release work? Is it sticky at any point?

While doubtful and I don't know if there is such a thing, but is there a super strong aftermarket rebound slide spring? If someone installed such a critter, it may be too strong for a weakened mainspring. The rebound slide spring is responsible for returning the trigger to its position of rest once pressure is released on the trigger.

Finally, while in the SA mode, try holding down the trigger. See if that makes any difference. Report back to us. Thanks.
 
Somebody altered the sear srufac e of the SA part. Now the DApawls or sear is no longer cleared by the falling hammer. Nothing to do with the rebound slide or main spring.

One remote possibility is a worn down, angle altered SA sear to let off easily, or just grit particles like desert sand on the sear.

However, S&W locks do not have problems unless somebody fiddles with them.

Regards

Winfried
 
However, S&W locks do not have problems unless somebody fiddles with them.
Click to expand...

Usually these are wise words of wisdom. It would be interesting to know if this revolver's current owner bought it new or used, and during the time he has owned it has there always been a problem, or did it recently develop?

In any case, someone who is qualified should remove the sideplate and find out exactly what is going on. All we can do is speculate.
 
Sounds like a screwed up attempt to lighten the single action trigger pull on a S&W revolver,by a previous owner.Have seen a few examples of this before.Remember a little knowlege can be a dangerous thing.It could require a new trigger or a new hammer if the case hardening has been cut thru,as it will not hold the the trigger pull.
 
I have tried to find out the correct term, but triggers often depend for proper functioning on the muscle of the trigger finger exerting force after the sear releases. If the trigger pull (SA) is too light, that will not happen and the sear won't clear a half-cock notch, or the hammer strut, or whatever else it needs to clear. If the trigger is too light, the muscle force required to pull it to release is not enough to continue to pull it and keep the sear out of hte way while the hammer falls.

Jim
 
I suspect the single-action hammer notch isn't correct. To see if that's the case, cock the hammer and see if you can push it forward without touching the trigger. If so, it needs good trigger work, probably including a new hammer. I recommend sending it to the factory.
 
I have tried to find out the correct term, but triggers often depend for proper functioning on the muscle of the trigger finger exerting force after the sear releases.
Click to expand...

I'm glad that somebody besides me has noticed this, and the problems it can cause aren't limited to Smith revolvers. I had a friend whose M1 could be made to fire doubles almost on demand with a super-slow trigger squeeze, but it never did it with a "normal" slow pull...call it a "Compressed Surprise Break"...used in a match.

OP. Did you check the side plate?
 
I have tried to find out the correct term, but triggers often depend for proper functioning on the muscle of the trigger finger exerting force after the sear releases.
Click to expand...

When the trigger releases the hammer, there should be no forward motion of the trigger, regardless of pull speed. It will only happen if the trigger return spring is too strong for the weight of pull. When I do trigger jobs, I either cut the return spring or replace it with a lighter one to balance the pull and trigger return forces. It's best for the pull to be a little stronger in release than the return spring force. That way, wear from smoothing won't cause the forces to become unbalanced.

The older K-Frames had internal trigger stops made with a screw and cam. The cam was rotated to provide minimal travel beyond the break, then secured with the screw. Holes can be found in frames long after the factory stopped installing the screws. I've used drill rod inside of return springs to provide a stop, but it's quite difficult to get the right length.
 
I agree with Picher. The trigger's forward movement is independent of the hammer and that it is the rebound slide that returns the trigger to its position of rest. Hence my question to Member ret621 to squeeze and hold the trigger to the rear.
 
The problem with the trigger stop was that under some circumstances it could block the trigger so that with the hammer cocked you couldn't release it. They discontinued it's use decades ago in all but a few target revolvers, and I don't believe they use it at all anymore.

It is highly improbable that it's playing any part in the current issue now before us.
 
Some pics of my SW 15

Again, I want to thank all who replied, and reading the replies showed that there were a few questions I needed to answer.......... I did buy the S&W as used about 15 yrs ago. At that time I am certain that it did work fine. I never fired it in all the time, and never had the sideplate off...until today. Here are a few pics of the internals, hopefully they MAY answer some of the questions, which I know are very hard to "see" without any pics!.... post1.jpg and post1.jpg I re-installed the plate very easily and it did not change anything in the original problem.
 
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