DA Revolver Trigger Jamming Problem

[Sanch]

I experienced a problem with my pre lock K-Frame. The hammer nose snapped. I figured it would be okay to keep dry firing it on snap caps for a bit (but jeez maybe I was damaging the frame in retrospect) and after about 100 dry fire cycles, the gun started locking up, trigger wouldnt work. I assumed it was the snapped hammer nose that got lodged somewhere inside.

I got the replacement hammer/nose today and installed it, same problem. With the hammer forward, the trigger wouldnt cock the hammer, it would get jammed up. I took it apart and reassembled and it seems to be working now. So I am not asking because I have to fix it, it seems to be fixed. I am asking out of curiousity so I can learn better how revolvers work and what caused this and what solutions for the future.

Also, I am worried its not that I reassembled the new hammer wrong, because as I said this problem started happening as soon as I snapped the hammer nose, before I ever took the gun apart, before I removed the original hammer. So maybe I didnt really "fix" it permanently, maybe I am just on borrowed time.

I snapped several pics.

First picture is where the actual binding is occuring. Excuse me because I dont know all of the names of the parts yet but I plan to learn! The trigger piece is supposed to interface like a gear inside the hammer, but instead its binding up here, as I am initially trying to press the trigger on a forward hammer:



Second picture is if I cock the hammer simultaneously as I press the trigger. It all seems to work fine when I do this. Whatever binding is occuring is removed if I "help" the trigger by manually cocking the hammer as I go and you can see the trigger nub properly connects into the hammer gear nubs:



These last two pictures are just of the gun cocked and uncocked, because maybe you can see something is assembled incorrectly:





So like I said, I took everything apart, including the hand (which fell out and I struggled to get the spring back in place lol), and reassembled carefully, and it seems to be working fine albeit a bit gritty on the trigger now, but I dont remember how it was before. I did install a whole new hammer so I wonder if the interface between the trigger and the hammer has to "Wear in" to smooth out over time.

I am asking as a learning experience, not a "help me save money I cant afford a gunsmith" question. I genuinely want to learn more about revolvers, this was my first time seriously taking one apart and it was a very fun 2 hour experience! I am blessed that I have two, and my second one is working fine so I took that side plate off and was able to compare and contrast.

[BN]

Don't cycle the revolver with the side plate off and full pressure from the hammer spring. That puts a sideways pressure on the hammer stud and it can break off. The side plate helps hold the hammer stud.

[Sanch]

Don't cycle the revolver with the side plate off and full pressure from the hammer spring. That puts a sideways pressure on the hammer stud and it can break off. The side plate helps hold the hammer stud.

Thanks, Bill, I will keep that in mind!

An update from the post, I did about 200 to 300 dry fire pulls today and then the gun stopped working again. This time, different issue, the trigger would fully "cycle" and the hand did actuate the cylinder but the hammer didn't move more than 1/4" back.

I took the gun apart and looked closer, comparing it to my good K-Frame and I looked at a schematic chart to figure out the name. It appears that the sear is slipping. The back part of the trigger isn't engaging between the bottom of the sear and the hammer. The trigger is hitting the sear, sliding past it, and jumps out of the notch it's supposed to remain in.

Looking at the two K-Frames, comparing good to bad, it appears the "good" one has the rear part of the trigger assembly more closely engaged to the sear when at rest with the hammer forward. So I'm wondering, maybe I have the wrong replacement hammer? It's identical to the original hammer that I got, but maybe that was also the wrong hammer that the previous owner put in. And maybe that contributed to the hammer nose snapping shortly after I purchased it.

Also, it appears the original sear that came with the gun is smoothed out where the trigger engages it, whereas one of the new sears is square on the bottom. I can take more pictures if this helps. I tried googling it but "sear slipping" wasn't generating any hits and that's the best way I can describe it.

I did notice the 200 to 300 dry fire pulls I did today before the gun stopped working again did feel "weird" and now that I see the problem, I realize what felt weird. I could feel the trigger was lifting the hammer only from the tip of the sear, not fully engaging it, so once the trigger cycle got halfway through, there was a slight jump in the action, barely noticable, but present. Also, I assume these 300 dry fire pulls were enough to cause the trigger to wear against the sear and smooth down that angle into a hexagon angle instead of square.

I'm not opposed to paying a smith to look at this, but since it's not a "duty" gun for me, I'd like to use this as a learning opportunity to learn more about revolver function. Already, I'm learning quite a bit!

[rsa-otc]

I have some thoughts but they have to wait until I check them out on one of my guns at home. As I understand it you replaced the entire hammer assembly and not just the hammer nose, Right?

[Sanch]

I have some thoughts but they have to wait until I check them out on one of my guns at home. As I understand it you replaced the entire hammer assembly and not just the hammer nose, Right?

Hi,

Yes, I replaced the entire hammer assembly. However, in looking at the original hammer that came inside the gun, the sear is worn down on there too in the same spot. So perhaps neither the original nor the new hammer assembly is correct?

Or, perhaps there's a step in reassembling that I missed, to ensure the sear engages with the rear part of the trigger properly?

I will say that the original hammer was also causing problems between the trigger and hammer, that started after the hammer nose broke. Although I cant say the hammer nose breaking is directly related to the previous issue and maybe just occured around the same time since I didnt own the gun too long before this happened. Specifically the trigger wouldnt engage the hammer. If I squeezed the trigger it would move only about 1/4" and the hammer was frozen in place preventing the trigger from moving back any more. If I cocked the hammer as I pressed the trigger, it cycled fine.

Now, with the new hammer, a slightly different symptom but I think also related to trigger/hammer fitment, which is I squeeze the trigger and it fully cycles the trigger, fully cycles the cylinder but the hammer doesnt move. In looking at it with the slide plate open, the trigger isnt engaging under the sear and is slipping off it, but the trigger is free to fully cycle. This is with the new hammer. Both hammers appear identical.

[RevolverRob]

1) Did you recover the broken firing pin nose from inside the action? If not, make sure you inspect carefully inside to confirm it or some other foreign materials are not lodged in the action.

2) Since you've had the sideplate off, you've had the cylinder crane screw loose. This screw must be TIGHT or the cylinder won't turn correctly and you'll get binding in the action. Reassemble everything - sideplate on - and tighten the screws - before doing anything else.

If you still get binding:

3) After this, disconnect the hammer spring and this will allow you to cycle the action - carefully (do not put sideways pressure on the hammer) with the sideplate off to look for binding. Make sure the cylinder is free to turn when you do this. A lot of binding occurs in Smith actions when the sideplate is off and the hammer spring is in place, so you definitely need to disconnect the hammer spring to diagnose your problem.

4) When in doubt, put the old hammer back in and check it for binding with hammer spring disconnected in the same way.

5) If you suspect the sear notch is binding, mark it with a sharpie or paint pen, reassemble the whole gun (including side-plate) and work the action, if it's binding the marks will allow you to know for sure where that is occurring. You can lubricate these areas with an oil, reassemble and try again and see if that helps.

6) If the old hammer works, you can drift the hammer nose pin out and replace the broken hammer nose with the new one from the new hammer assembly.

[BN]

It's been a while since I messed with S&W revolvers, but be aware that single action and double action use different parts.

[RevolverRob]

It's been a while since I messed with S&W revolvers, but be aware that single action and double action use different parts.

Bill, do you mean that the SA and DA actions use different sear notches on the hammer? This is true.

Make sure you have them lined up properly or DA will never work right!

[rsa-otc]

Keep in mind that revolver especially the older ones where hand fitted on assembly and changing up parts can cause issues without further fitting. Some times the difference is only a few thousands of an inch. Which parts may look the same the tolerances may just be slightly off.

A couple of observations, the only time I personally have seen a hammer nose break is when it strikes the frame as it enters the recess just below the rear sight. Usually this was a wear issue or dirt between the hammer & hammer nose that kept it in a more upward position. The older Smiths use to have a small spring as part of that assembly that would push the hammer nose down. Without inspecting your old hammer I can only guess as to the reason it broke off. I Wouldn't ever expect a hammer nose on a centerfire S&W revolver to break from dryfiring it. Especially if you were using snap caps.

On to your current issue. Again without personally inspecting the parts I think two issues could be causing your current problem. I think the spring loaded part of the hammer that interfaces with the trigger is not fully returning to an extended position. This could either be from a weak spring, dirt or wear. My guess is it has debris keeping it from freely moving back and forth. Remove the hammer and try and depress this part (I forget the name and I don't have a schematic here at the house lets call it the DA sear) and see if it move freely. Check the top and see if there is dirt lodged in there that isn't allowing it to return to a fully extended position. Cleaning it liberally with breakklean and lubricate it with a light oil. Back in the day S&W didn't want us to lubricate the internals of the revolvers because over time it would collect dirt and gum up. Also the older oils would turn rancid and gummy over time cause the action to be sluggish or jam up. Not something you want to happen on a service pistol. Given today's lubricants and the fact this is a range toy I would use a quality oil and not worry about it. Especially since you don't seem to adverse to tearing the gun down when needed. Back in the day guns sat in holsters and were not tended to for extremely long periods of time.

When the hammer and trigger interface was binding during the double action stroke as indicated in you first picture. Either the DA sear wasn't fully extended at the time or it is a hair shorter than the original not lifting the hammer enough to avoid the interference. It may be just a couple of thousands off either through wear in the original gun it was installed in or thats how the original gun was fitted together.


Personally I put a drop of oil on each axel/stud, where the rebound spring block rubs on the frame and in the channel the drop safety slides in the side plate.

Hopefully this helps. Good Luck

[Wayne Dobbs]

Smith and Wesson revolvers are not drop in parts guns, especially the pre-lock and pre-MIM guns. You need a competent gunsmith to fit that part correctly. As you've discovered at this point, just because it drops in doesn't mean it works.