Hammer question on a 4536

[swmetal]

Need some insight on the hammer behavior on my 4536. I only had it to the range once since getting, fired fine. Was going over it today and noticed something strange while dry firing. When pulling the trigger in either single or double action, the hammer appears to hit the firing pin but then return to the decock position (picture 1) rather than fully forward (picture 2). This happens 9 out of 10 times, but once in a while the hammer does return to the fully forward position.

Any ideas what is going on?

 

[armorer951]

Try dry firing with a snap cap or an empty casing. My guess is the hammer is rebounding for some reason.....perhaps it's being "re-impacted" by the firing pin. Not sure what would cause this....perhaps a non-OEM firing pin spring??

 

[robtom]

I also have a 4536 and a 469 that do this. I replaced the mainspring in the 469 and it was remedied. I have not done anything to the 4536. I think it has to do with half cock notch of the older autos and frame mounted decocker models.

 

[JohnHL]

I'm not all that familiar with the frame decocker models but I didn't know any 3rd gen model hammers had a half cock notch like the 1st and 2nd gens did.
Could someone have installed a 2nd gen hammer?

John

 

[swmetal]

I'm not all that familiar with the frame decocker models but I didn't know any 3rd gen model hammers had a half cock notch like the 1st and 2nd gens did.
Could someone have installed a 2nd gen hammer?

John

I found the manual here, http://stevespages.com/pdf/s&w_centerfire_pistol_decocker.pdf, which states the decocking lever in the 3rd Gen frame mounted decockers returns the trigger to the half-cock notch so hammer appears original.

I think armorer951 is correct about the hammer rebounding as the issue goes away when I use the method of putting a pencil in the barrel and dry fire. Still would be good to know if this rebounding is "normal" behavior or not. I may install a spring kit in the future.

 

[JohnHL]

Thanks, swmetal. That's fascinating.
So if the frame decock models have a half cock then I wonder if the occasional slip off the half cock notch is an indication of wear or damage.
If you deliberately decock the the hammer to the half cock notch, will it push off with moderate thumb pressure?

John

 

[BLUEDOT37]

I've observed this on my 1076 & 845 autos. (They both have half-cock notches. 1076 has frame decocker & the 845 has no decocker.) They both have new compliments of Wolff extra power springs in them. (They did it before I changed the springs too, as best I recall.) Without something to absorb some energy from the firing pin (fired case, Snap cap, pencil down the barrel) they bounce back & stop off normal.

I suspect it's the firing pin spring pushing it back but I've never tried it without that spring. (Honestly I can't see a bounce. It looks like it just stops short but that doesn't make any sense.) They won't push off from this state either.

.

 

[swmetal]

I've observed this on my 1076 & 845 autos. (They both have half-cock notches. 1076 has frame decocker & the 845 has no decocker.) They both have new compliments of Wolff extra power springs in them. (They did it before I changed the springs too, as best I recall.) Without something to absorb some energy from the firing pin (fired case, Snap cap, pencil down the barrel) they bounce back & stop off normal.

I suspect it's the firing pin spring pushing it back but I've never tried it without that spring. (Honestly I can't see a bounce. It looks like it just stops short but that doesn't make any sense.) They won't push off from this state either.

.

Sounds like this may be 'normal" behavior then. I agree, the bounce is imperceptible and I thought the hammer was stopping at half cock until I put a pencil in the barrel.

 

[armorer951]

You could send S&W Customer Service an e-mail and describe the issue. They might have an opinion concerning whether this is "normal" or not. I suspect it's not an issue as far as proper function of the gun....although I've never seen this in any of the autos I've inspected over the years.

If you are not the original owner and are not familiar with the history of the gun, you might consider changing out the existing hammer and F.P. springs for some new OEM ones. If you decide to replace the springs, be sure to clean the firing pin tunnel, and the firing pin prior to installing the new spring.....and leave the tunnel and components dry when you re-install. The 2nd and 3rd gen guns I've inspected and worked on over the years were all notorious for attracting dirt and debris into this area.
It's a good idea to clean and inspect this area regularly, epecially on EDC guns. Check the F.P. spring for wear along it's entire length with a magnifier. I clean this area and components with a Liquid Wrench product called "Dry Lube". It has a very volatile carrier, and leaves no residue. As always, read and follow the label instructions and warnings.

 

[dmc8163]

The hammer behavior you describe is perfectly normal for the 4536. The hammer will not push off from the half cock position. There is no need to replace the spring. D

 

[BLUEDOT37]

Hammer stops at half-cock on empty chamber issue

I pulled out my 1076 to take it to the range today & started thinking about this "hammer stops at half-cock on empty chamber" issue.

I came up with a theory on the problem that I can resonably confirm. I think that with an empty chamber the slide is slightly (a few thousands?) forward from where it normally is with a cartridge in the chamber. Manually pushing the slide every so slightly rearward with me free hand & the hammer falls fully forward without this problem occuring.

I also confirmed the theory by chambering an unprimed case & repeatedly firing the gun both SA & DA without any stoppages at half-cocked. Nothing to absorb the firing pins energy but the case still spaces the slide/barrel normally.

I'm not intimate with the internals/timing on these guns so I can't state exactly whats happening to cause it, but that's my observation on it.

By the way, the 1076 functioned flawlessly at the range, as usual. I forgot how well, & accurately, it shoots as it's been awhile since I've taken it out to play. It'll be tagging along with me for a while now.

.