S&W 38 Double Action

[johnm1]

Bare with me. I'm typing this on my handheld and it is old. I managed to find the parts I was missing for a 38 DA 3rd model.

(photos in this post http://thefiringline.com/forums/show...+double+action ).

I found a parts gun with bothe the side plate nut and hammer I needed. The latching mechanism is tight and timing is good.there are 2 things that are odd/concerning.

First is the firing pin does not retract after the trigger is released. Was this normal for a 38 DA third model?

Second, I can stage the double action trigger pull and leave the hammer on the single action notch. Is this normal or is this an artifact of a replacement trigger not being fitted to the gun?

[James K]

The firing pin does not retract; there is no hammer rebound mechanism.* On the condition you describe about the SA sear engaging the hammer on a DA pull, I can only say I can't get mine to do that, but it is very close. In normal DA the sear is removed from the hammer notch just before engagement. If the SA works OK and the hammer doesn't show any tendency to hit the sear in normal (non staged) DA, I wouldn't worry about it. But, yes, those guns are made to very close tolerances, and installing replacement parts is tricky to put it mildly.

*Hammer rebound was not needed on a top break because opening the gun cammed the hammer back from the fired primer. It was not until swing-out cylinders came along that the firing pin had to be retracted to allow the cylinder to be opened.

Jim

[johnm1]

Thanks James.

[Mike Irwin]

"Second, I can stage the double action trigger pull and leave the hammer on the single action notch."

I agree with Jim, as long as you're not getting the hammer and sear lashing when the trigger is used double action it's probably not that big of a deal, but it's definitely not entirely normal operation.

[johnm1]

Thanks Mike. I figured it wasn't normal. But the rest of the fire control works fine.

The lack of a hammer rebound is the greatest concern. The sight of the firing pin extending through the frame is disconcerting. Just seems it is an accidental discharge waiting to happen.

[Mike Irwin]

That's why those guns are treated the same way you treat a traditional single action -- EMPTY CHAMBER UNDER THE HAMMER.

Iver Johnson was the first manufacturer to introduce a safe and reliable mechanism -- the transfer bar safety -- for ensuring that the firing pin wasn't resting on a primer, allowing the gun to be carried fully loaded.

With the transfer bar safety, the hammer never actually contacts the frame-mounted firing pin. When the trigger is pulled all the way to the rear, the bar moves up between the hammer and the firing pin. The hammer hits the bar, and transfers the energy to the firing pin.

When the trigger is released, the bar moves out of the way.

It was virtually flawless, and in reality was a safer mechanism than S&W's original rebounding hammer. Early models didn't have a hammer block, so if the gun were dropped, the hammer could shear and the gun could fire.

Later models did have hammer blocks, but their function wasn't certain. It wasn't until 1944-1945 that the modern S&W positive hammer block safety was introduced.

[James K]

I will have to say that those guns have a "safety notch" that allows retraction of the hammer so it is not resting on the primer but, like the "safety notch" on the SA Colt, it cannot be trusted to keep the gun from firing if dropped on the hammer. So a big + to Mike for the reminder to "load 5" (or 4 as the case may be).

Jim

[johnm1]

Interesting Jim. Neither hammer I have engages a safety notch. The old hammer was cracked at the mainspring conection and had the single action nothc ground. So I wasn't sure if it ever had a safety notch. Once I replaced the hammer and still had no safety notch I assumed the design didn't have one. I really need to study the action and understand how it works. Maybe I nEed yet another hammer or possibly some other part. A safety notch would be preferred.

I also want to understand the ability to stage the trigger and engage the single action notch. Wonder if the two odd conditions are related.

[McShooty]

On my Third Model, the "safety notch" is reached with just a very short retraction of the hammer. It makes a tiny click and seems positive. The point of the firing pin is held away from the primer position, but the point still protrudes a bit in front of the recoil shield.

I can also stage the hammer during a double action pull, but it won't remain in the single action cocked position. If I pull through, it will fire, but if I let the trigger go forward, the hammer comes down without breaking.

This staging seems a rather desirable function. With a little trigger finger education you can essentially fire the gun single action without having to disturb your grip by thumb cocking. I once emptied the gun (5 rounds) by staging and firing while keeping my grip undisturbed.

I haven't personally seen very many examples of these models. I don't know if the staging is a standard operational feature or not, but I think it is possible that it could be. You can see that this would be very desireable in the safety hammerless line of S&Ws because it would allow an approximation of single action shooting with a gun that is impossible to cock.

[johnm1]

Thanks McShooty. On mine with the slightest movement backwards of the hammer the cylinder stop drops out of the way and the cylinder free wheels. But no hint of engaging a notch. I still haven't researched how the action works. Meaning I haven't taken the side plate off to see where the safety notch should be and what it is supposed to engage with. I found the single action notch and it is tiny. Do you know where the safety notch is on the hammer?

I am pretty sure the staging of the single action is an artifact of an ill fitting replacement hammer. I fear that this condition may wear that tiny SA notch. So if I can figure ou how to, I will correct. Others on this forum indicate that it is not normal.

Thanks for the reply.

[McShooty]

I am sorry I can't tell you where the safety notch is on the hammer. For what it is worth, I have an S&W top break 32, 4th Model, that functions in exactly the same way. The safety notch engages with just a smidge of hammer retraction, and the double action pull stages beautifully for a single action let-off. Even more positive than on my .38.

[johnm1]

I'm just going to have to take it apart and study the action. Thanks for all of your help.

[Mike Irwin]

Staging the trigger is one thing. I can stage the trigger with all of my J frames, pulling it about 2/3rd of the way through the double action pull to a... set point, for lack of a better term... and then the final 1/3rd of the way through with it feeling very much like a long single action pull.

What will NOT happen, however, is the gun staying cocked single action when the trigger is released.

If any double action handgun is doing that, it's a mechanical issue.

[johnm1]

Agreed Mike. And this may be related to the lack of a safety notch. I think I have identified how I think the safety notch is supposed to work. The safety notch appears to be a function of the sea as it rests in the double action notch on the hammer when the gun is un-cocked. By moving the hammer back the slightest amount two thing happen. The cylinder stop drops slightly allowing the cylinder to free wheel. And the sear, on top of the trigger assembly, rises ever so slightly. It appear there should be more metal below the sear that engages the double action notch on the hammer holding the hammer back slightly. It appears this extra piece of metal is missing from below the sear on this gun. That would explain why this gun didn't have a safety notch with either hammer. I do have a parts gun that I can inspect and possibly exchange parts. That will have to wait until I return home this weekend. How this may be related to staging the trigger isn't quite clear yet. But that same sear is what allows the trigger to be staged.