Help me not Make a Mistake

[Johnm1]

I own 4 S&W Double actions. A 32, two 38's, and a 44. The 32 and one of the 38's can't be pushed off and will not release from single cock when the firearm is struck with a plastic mallet. Call it the hammer test. One of the 38's and the 44 are difficult to push off but fail the hammer test and will release from the single cock notch when the firearm is struck with a mallet. I just acquired a Marlin that is almost an exact copy of the S&W 38 DA that can't be pushed off but also fails the test.

While testing the Marlin I noticed that when it fails the hammer test the trigger is pushed forward. To me that indicates that the front sear is applying too much upward force to the hammer when the hammer reaches the single cock notch. The obvious solution isnto remove some material from the contacting surface of either the front sear or the hammer. Hammers are hard to come by, though I have a couple, while front sears are plentiful.

So before I do something stupid I'd like opinions on my thought process. Because the action is ancient I have marked up a couple of pictures. Also, this animation, which I've referenced several times in the past, is really helpful.

S&W 38 DA 3D anim

3D animation Smith & Wesson Top Break Double Action 38 Revolver action

youtu.be

Thank!

 

[NIGHTLORD40K]

As long as you're not planning on carrying these, keep the muzzle pointed downrange and it shouldn't be an issue. I'd leave 'em alone.

 

[Johnm1]

As long as you're not planning on carrying these, keep the muzzle pointed downrange and it shouldn't be an issue. I'd leave 'em alone.

The 32's and 38's are range toys and thats what I do with them. I'd like to carry the 44 as my hunting sidearm. That would entail holster carry all day. Except when hunting in handgun season it has never left the holster. In handgun season it is fired in double action.

Plus there is that anal retentive side of me that wants it perfect.

 

[Johnm1]

Well, that theory was a bust. I removed all of the force using a spare hammer (I have 4 spare hammers and no Marlin front sears) and it did not cure the issue.

FYI , when I disengage the front sear and allow the trigger to return it cannot be pushed off and it passes the hammer test.

I can see that the rear sear is engaged with the single cock notch on the on the hammer ever so slightly different with the trigger pulled back compared to when I disengage the front sear and allow the trigger to return while keeping the sear engaged on the single cock notch.

More research. Translation, I’m going to stare at it a while longer.

 

[film495]

staring is good. say some mean things too. out of curiosity, how hard are you hitting the hammer with a mallet? I've always just given the hammer a good push with my thumb and called it good. still never seen on push off. search it online, I be there is someone fixing this exact issue on a S&W double action.

If they are all similar mechanically, having a good working sample to study how it works and compare is a blessing.

 

[Johnm1]

staring is good. say some mean things too. out of curiosity, how hard are you hitting the hammer with a mallet? I've always just given the hammer a good push with my thumb and called it good. still never seen on push off. search it online, I be there is someone fixing this exact issue on a S&W double action.

If they are all similar mechanically, having a good working sample to study how it works and compare is a blessing.

Not very hard. A solid tap is more like it. Less than the force applied if I dropped it from mid-chest. I can still push the Marlin off. It does take a bit of force. It also fails the hammer test.

Apparently I’m the only idiot trying to fix these things.

Oddly I got the second S&W 38 to hold and pass the hammer test just by swapping hammers. I managed to get the 32 and the first 38 to hold and pass the hammer test by swapping parts. I have no idea what changed when I swapped parts. One was a front sear and two were hammers. Reality is I’m just a parts swapper.

In all cases the single action will hold if either the mainspring or front sear are disengaged. No amount of force can push it off if either is disengaged. Not sure what that tells us though.

So it doesn’t appear to be either a rear sear edge or hammer notch edge.

 

[film495]

no idea, but when I get one of those and have the same problem, you can remind me how to fix these ... lol

 

[Johnm1]

no idea, but when I get one of those and have the same problem, you can remind me how to fix these ... lol

If I ever figure it out I will. Right now all i can suggest is to have a pile of parts and start swapping.

I started the day with the Marlin holding almost every time but not passing the hammer test. The same parts are in place and it pushes off. It takes quite a bit of force to push it off, but it changed after disassembling and reassembling. When I first got it the 44 DA wouldn't hold at all on single cock until I saw that someone had repaired the hammer pivot pin poorly. That repaired pivot pin wobbled. The replacement doesn't wobble but like the Marlin it can be pushed off if I push hard enough.

I'm thinking 120 years of wear comes into play.

 

[film495]

kind of makes me wonder if wear and some flex in the pivot pins isn't the root of the problem. what does it feel like when it pushes off? do you feel any flex, or is it crips like a trigger break?

 

[Johnm1]

kind of makes me wonder if wear and some flex in the pivot pins isn't the root of the problem. what does it feel like when it pushes off? do you feel any flex, or is it crips like a trigger break?

I don't think I can give a comparative description. There certainly isn't any felt flex when I pull the trigger.

I noticed the hammer pivot pin was messed up visually. As I pulled on the hammer I could see the pivot pin move with my unaided eye. But that pin was butchered `significantly ` I found that issue by just staring at it. I can't see any movement in the action, but I don't expect wear would be great enough to visually show movement. I'll keep looking though as something has to be changing.

 

[film495]

do you have a decent magnifying glass?

 

[Johnm1]

Yes. How can that be used to find wear?

I also have a coin microscope that was advertised to reach 1400X. It's Chinese and the instructions weren't good enough for me to figure out how to verify magnification, but I can get very high magnification with clear views. I think it uses both optical and digital magnification. It takes pictures and video too.

 

[Johnm1]

I noticed the hammer pivot pin was messed up visually. As I pulled on the hammer I could see the pivot pin move with my unaided eye.

I thought I wrote this in the above post, but the hammer pivot pin that was messed up was in my 44 double action. Not this gun.