1076 single action falling to half cock

[10 X]

I recently got a 1076 and found that I needed to replace a broken trigger play spring.

Prior to receiving the parts, I shot 75 rounds without any problem other that the click in the SA trigger pull. I replaced the trigger play spring (that is a story in itself-what a job!) and recoil spring. I then shot 75 rounds mostly in single action without any problem.

In dry firing today, the gun drops the hammer to half cock rather than full fire inconsistently.
Sometimes it will sometimes it won't. Cocking was done by either pulling back the slide partially or fully or thumbing the hammer to full cock. I am squeezing the trigger easily, just like I would at the range. No consistency.

Any idea what is causing this?

 

[cpeblue]

I asked this same question once and heard crickets.My problem was the same, dropping on half cock randomly on both of my 639s. What I ended up doing was to replace 1 with a gen3 hammer and the 2nd one I filed down the half cock step on the hammer. Both work flawlessly and I've put about 700 rds through each. I don't know how many times I took them apart trying to fix that problem and kept coming up the same. So it may have been the easy way out but it worked. I don't know what a 1076 is but I did think it was a 3rd gen.

 

[Gunhacker]

Try replacing the hammer main spring. I sent my 1076 back to the factory for similar symptoms and that's what they did... it has been working flawlessly ever since.

 

[10 X]

A 1076 is a 3rd gen 10mm 4.25" barrel with a decocker on the frame.

Before I do anything more, I will see if there will be more responses.

 

[Gunhacker]

Check out this thread... does it describe what you're encountering? I know... this involved a 39-2 2nd gen pistol, but the differences in the lockwork (drawbar, sear, disconnector, etc) of a 2nd and 3rd gen pistol (even a frame decocker) is not all that drastic.

http://smith-wessonforum.com/smith-...0-need-model-39-2-gunsmith.html#post136204024

 

[cpeblue]

The only frame decockers I have are Sigs and I never had that problem with them. Sorry

 

[cpeblue]

Gunhacker, interesting thread. The mainspring was the 1st thing I changed on the 639s and I thought that was it . It changed the frequency of the problem to say once every 150 shots. That was unacceptable and I never had that problem with the 3rd gen 39 or 69s so I did the hammer changes and MY problem was gone. As I said I have no history with Smith frame decockers so a fresh mainspring is a good start.

 

[bishopm14]

I have a 1076 that does this as well. But in the time I have owned it, roughly 300-400 rounds, it has never misfired when actually shooting.
My theory, the hammer isn't stopping at half-cock, but rebounding to half- cock when dry fired in single action. Otherwise, I don't see how I have had no misfires.
I may be wrong, but as long as live fire works, I don't worry about it.

 

[BLUEBELLYYANKEE]

I have seen this before a couple of times. The first thing that should be done is to find out if the gun was repaired under the S&W recall from the 1990's. Look under the decocking lever and see if you see two dots that were punched into the metal frame of the gun. These two dots reside under the black plastic thumb piece when the decocker is at rest. If no dots then the gun needs to go back to S&W for the recall. This recall may fix your problem. If the recall was done then you need to disassemble the gun entirely and make sure it is absolutely clean. The parts that are contained in the frame must be clean without any residue/dirt build up in order for the decocking system to work reliably. It takes very little movement of the clockwork in these decocker guns to drop the hammer and return to double action mode. If there is some build up of dirt in just the right area then this could certainly cause your problem.

If you feel that action is clean then make sure you replace the trigger rebound spring and hammer spring with new ones. These springs being weak could be contributing to the problem because the timing of the action is not what the gun needs to function.

Hope this helps.

 

[10 X]

The two dots are there. I looked at that before I bought the gun. The gun is clean. It was clean when I started and was thoroughly clean and lubed after I finished with the trigger play spring and reassembly.

I am convinced. I should have mentioned that I got new S&W grips with the other parts.
I tried my old grips and the gun doesn't stop at half cock, only with the new grips and only now and then. So, the problem is in the main spring area.

I should have thought of that. I had a similar problem with a Gold Cup 25 years ago.
Sometimes it wouldn't drop the hammer. No one could tell me what the problem was. I ended up fixing the problem with a new main spring. The old spring was compressed to too short a length from years of being left cocked.

 

[BLUEBELLYYANKEE]

"I tried my old grips and the gun doesn't stop at half cock, only with the new grips and only now and then. So, the problem is in the main spring area."

If you are experiencing different results with a change of the grips, make sure that you have the grip "driven home" into the back of the beaver-tail. That plastic grip should be perfectly smooth with the metal frame of the gun under the beaver tail. If the grip stands proud of the frame by about a 1/16th of a inch then a good squeeze will snap it into place.

 

[10 X]

A follow up
I got a main/hammer spring kit from Wolff, six springs of various weights.
I put in the 20 lb. spring (factory weight) and it helped, but did not cure the hammer from dropping to half cock rather than firing (when dry firing).

I put in the 22 lb. spring and that stopped it. It dry fires every time.
However, now there is a big hitch in the double action pull around the half cock point.
I don't know what to do about that. There is no way to accurately shoot this DA.
The SA is of course heavier, but tolerable. The last thing I wanted was a heavier trigger pull let alone the hitch in the pull.

I really wanted to like this gun, but I am at the point of getting rid of it and getting rid of the frustration.

Anyone have thoughts of what I could do about the "hitch"?

 

[mbliss57]

If you call S&W and get a return authorization they should take care of the problem for you. I was frustrated with a Ruger I had in similar circumstances..(tried all kinds of things to fix a FTE problem) finally I just returned it.. let them fix it and have been hassle free since. S&W has a lifetime warranty on their firearms.
Let them handle your hassle.

 

[handgunner356]

Try putting your original spring back in. Take a pencil with a good eraser on it and with a empty gun place it down the barrel againest the breechface. Then try dry firing it and see if it sends out the pencil and ends up in the half-cock positition. If the gun works every time on the range I'm betting that the hammer is bouncing back onto half-cock.

 

[ShelbyV8]

Unless frame decocker pistols are different 3rd generation pistols don't have a half cock notch on the hammer.

 

[10 X]

I put in the 20 lb spring and then tried an 18 lb spring. It doesn't stop at half cock any more or less with the 18 vs. the 20. I tried the pencil test before and today.
It will not go to half cock with the pencil. I couldn't get it to do it even once.

If it is rebounding to half cock, what causes that? A weak sear spring? Wrong setup on the decocker pawl?

 

[handgunner356]

Normally the instant the hammer falls the slide is coming back to recock it, when you dry fire this isn't happening. With the heavier hammer spring it doesn't bounce enough to overcome the spring like it is with the lighter one. I have several guns that will do that mainly because I use lighter hammer springs in them. Don't fret, just shoot, be happy.

 

[10 X]

Well it worked fine for 150 rounds when I shot it, so, I have to believe it will work.
Anyway, I am going to go to the range tomorrow or the next day and test it again.
I just have never had a gun do this before.


I shot it again yesterday. Again, absolutely no problems. Like handgunner356 said, just shot and was happy.
9 rounds will stay in a four inch circle at 25 meters.