S&W Hammer Camming Forward Problem 586-8

armorer951 said:
I'm not sure I'm permitted to show a Youtube video link here or not.....or if it will work. Be advised that the video runs in slow motion, (very slow) and shows just the end of the trigger recovery cycle. Wait for it, or fast forward to about 0:55.

It's a de-milled 686 frame and internals........


YouTube
Click to expand...

Watched it many times. It seems to me the only way for the hammer to go forward on a trigger pull in which the trigger is all the way forward and the hammer is at rest is if the rebound slide is out of the way. Like it's not returning forward at all! Do I have that right?
 
Here's a link to several revolver action static drawings that show the position of the various components in single action and double action. These may help you to visualize what's actually happening.

In double action in your scenario, if the trigger is pulled fully to the rear, it will complete it's course after bypassing sear in the the hammer. Consequently, this rearward movement of the trigger removes the rebound slide from under the hammer, just like it would if there was no malfunction. The gun should work normally if cocked single action. If the DA sear is out of service, as in this case, DA will not function correctly.


http://smith-wessonforum.com/s-w-smithing/587466-revolver-action-drawings.html#post140391266
 
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armorer951 said:
Here's a link to several revolver action static drawings that show the position of the various components in single action and double action. These may help you to visualize what's actually happening.

In double action in your scenario, if the trigger is pulled fully to the rear, it will complete it's course after bypassing sear in the the hammer. Consequently, this rearward movement of the trigger removes the rebound slide from under the hammer, just like it would if there was no malfunction. The gun should work normally if cocked single action. If the DA sear is out of service, as in this case, DA will not function correctly.


http://smith-wessonforum.com/s-w-smithing/587466-revolver-action-drawings.html#post140391266
Click to expand...

Ok I think I've got it now. Its almost positively the sear not resetting then correct? The sear is staying behind the tail on the trigger instead of slipping on to the top surface and when this happens its actually camming the hammer forwards instead of back.

50047876533_8561a4382d_b.jpg
 
Sort of....the hammer is moving forward because it's under spring tension provided by the mainspring. In your scenario, the DA sear in the hammer is bypassed by the trigger, but the other actions caused by the trigger continue as the trigger is pulled rearward, including the cylinder rotation caused by the hand.

As the trigger continues to be pulled back, what's called the the "hammer seat" on top of the rebound slide moves back, allowing the hammer to move forward (under mainspring tension) to the position it would be after falling into battery. This is because the rebound slide has moved back, and out of the way.


 
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armorer951 said:
Sort of....the hammer is moving forward because it's under spring tension provided by the mainspring. In your scenario, the DA sear in the hammer is bypassed by the trigger, but the other actions caused by the trigger continue as the trigger is pulled rearward, including the cylinder rotation caused by the hand.

As the trigger continues to be pulled back, what's called the the "hammer seat" on top of the rebound slide moves back, allowing the hammer to move forward (under mainspring tension) to the position it would be after falling into battery. This is because the rebound slide has moved back, and out of the way.


Click to expand...

Is it likely then that the double action sear spring is the culprit?
 
Armorer has tried to walk you and listeners through the interplay of parts but I'll just add that it's real tough the solve a problem like this without having the gun on the bench. Either way I'm just going to say that I'm pretty sure somebody has monkeyed up the trigger or hammer or both. Even clipped rebound springs don't cause hammer tripping like the video. You need a qualified mechanic to solve this

Good luck
Rick
 
garbler said:
Armorer has tried to walk you and listeners through the interplay of parts but I'll just add that it's real tough the solve a problem like this without having the gun on the bench. Either way I'm just going to say that I'm pretty sure somebody has monkeyed up the trigger or hammer or both. Even clipped rebound springs don't cause hammer tripping like the video. You need a qualified mechanic to solve this

Good luck
Rick
Click to expand...

Thanks for your input but I'll state again the gun has not been monkeyed with or modified in any way at all. Bought new a couple years ago, shot very little. It will go back to S&W I just wanted to learn from it.
 
I have had this happen twice on two different guns. Same part on both ... rebound spring.

First one was a used 29 DX I bought, found out after first range session that someone had clipped a few coils off the rebound spring.

Second one was a 629-4 Classic that I bought new and shot a LOT. Only modification was polished internals shortly after purchase. Rebound spring the gun was made with was 3/16" shorter than a new one.

I hope your fix is as easy as mine were and you don't have any damaged DA surfaces.
 
I have watch this thread intently and have ideas but without gun in hand, it is tough. I think rebound spring and also dont like the looks of the double action sear as I was taught it should have a bevel on the bottom of the front side that I dont see here. Hopefully you will get an answer from factory repair but I would not bet on it.
 
I had a similar issue once, worked fine in single action but wouldn't fire in double action. When I removed the side plate the only thing I could find wrong was large burrs on the corners of the rebound slide. I stoned them off & it worked fine afterwards. Apparently jammed it up so the hammer didn't seat.
 
ken158 said:
I have watch this thread intently and have ideas but without gun in hand, it is tough. I think rebound spring and also dont like the looks of the double action sear as I was taught it should have a bevel on the bottom of the front side that I dont see here. Hopefully you will get an answer from factory repair but I would not bet on it.
Click to expand...

The second slow motion of the internals is not my gun, another member added that to show the technicals of the reset.
 
Master revolver smith Will O'Hara confirmed that the DA sear doesn't have enough clearance or "wink" as they call it. I confirmed this with a .010 thousandths feeler gage and it wouldn't clear. I put the DA sear in a mini precision machine vise keeping the angle of the sear nose and stoned it. I had to do this twice as the first time wasn't quite enough. I put it back together and couldn't get it to malfunction unless I intentionally tried to by short stroking it. I took it apart again and put in a Wilson spring kit and it feels awesome. Thanks for all the input.

[ame]https://www.youtube.com/watch?v=I-K2u-wcmkk[/ame]
 
armorer951 said:
If you think about it and don't mind, try to give us a report on what was determined to be wrong when you get it back.

Thanks,

Carter
Click to expand...

Warranty they usually don't take the time to explain anything. Probably put a hammer and or trigger in it and send it back.
 
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