S&W Hammer push off?

[Webleymkv]

I have a bit of a conundrum with my S&W 629-6 as I recently had to replace the hammer in order to correct a case of hammer push off. I noticed that the SA trigger on my revolver had become extremely light and, while I've seen worse cases, when tested the gun did have a case of hammer push off. Now, we all know that the most common cause for hammer push off is amateur gunsmithing but I know that such was not the case with my revolver as I bought this gun brand new roughly 15 years ago and have never modified the internals other than to swap out the mainspring and rebound slide spring (the factory springs have since been re-installed). In examining my old hammer, the SA notch did appear to be worn as compared to the new one (though the notch is so small it's difficult to tell) and I also noticed what appeared to be a small chip on the SA "leg" of the hammer.

Replacing the hammer with a new one seems to have cured the problem as I can no longer produce hammer push off with reasonable pressure and the SA trigger is back to what I'd consider normal. Does anyone have any idea what might have caused the abnormal wear to the original hammer? I have a couple of hypotheses, but I'm not sure how likely they are. One possibility is that several years ago I did have the firing pin break (it was repaired by S&W) and perhaps part of the firing pin swimming around in the action chipped the SA "leg" of the hammer which, with several years more wear, caused the problem (though I'd think S&W would notice the damage to the hammer when the gun was sent in for initial repair). The other possible cause is that I polished the exterior of the gun (though I did not remove the sideplate or internals when I did so) and perhaps a bit of polish found its way into the action and gradually wore the SA notch of the hammer (though the trigger exhibits no abnormal wear that I can detect).

[4V50 Gary]

Hammer sear gets worn. If it's mim, then once the hardened surface is gone, it wears out rather quickly.

[dahermit]

Originally Posted by 4V50 Gary

Hammer sear gets worn. If it's mim, then once the hardened surface is gone, it wears out rather quickly.

If I remember correctly, it has nothing to do with MIM. The hammers and triggers, etc. were case hardened way before there were MIM parts and once the case is worn through, softer steel underneath wears more rapidly as you stated.

[44 AMP]

The hammers and triggers, etc. were case hardened way before there were MIM parts and once the case is worn through, softer steel underneath wears more rapidly as you stated.

This is, and always has been true. From what I read on the Internet (take that for what its worth) MIM parts will wear faster than traditional steel parts once the hardened surface is worn through.

No idea if that true, or not, just that's there's a lot of talk...

[tangolima]

Do you shoot a lot of SA? If you do, the sear engagement will get worn to negative to cause push-off.

It can be repaired, but it is a professional job. Replacing parts is easier. Applying good grease to the engagement surfaces will help lengthening the life of the proper engagement.

-TL

Sent from my SM-N960U using Tapatalk

[Aguila Blanca]

Originally Posted by dahermit

If I remember correctly, it has nothing to do with MIM. The hammers and triggers, etc. were case hardened way before there were MIM parts and once the case is worn through, softer steel underneath wears more rapidly as you stated.

The pistol was purchased new 15 years ago. MIM parts have been with us much longer than 15 years.

But I think you were implying that the hammer and trigger are case hardened. I doubt that S&W was using case hardening 15 years ago. I think those parts would have been heat treated, which would generate a much more homogeneous through hardening.

[Scorch]

The problem with hammer push-off usually has nothing to do with the hammer. It's usually the trigger. Recutting the trigger usually solves the problem.

You either know or you don't know. The trick is knowing what box you fit in.

[dahermit]

Originally Posted by Aguila Blanca

The pistol was purchased new 15 years ago. MIM parts have been with us much longer than 15 years.

But I think you were implying that the hammer and trigger are case hardened. I doubt that S&W was using case hardening 15 years ago. I think those parts would have been heat treated, which would generate a much more homogeneous through hardening.

Case hardening is heat treating. In case hardening, the part is packed in a carbonaceous material and heated until the carbon is infused into the part for a few thousandths. Then the part is quenched from a heated state to harden that outer skin. Case hardening is shallow, but it is still in the realm of heat treating albeit not through hardening as would happen if the entire part was high carbon.

As for how long or when S&W used case hardening on hammers and triggers, I do not know other than the conventional wisdom in the gun rags has been that they were in fact case hardened way back in the sixties when I was reading most of the gun rags in those days. There was always a sage warning not to "take too much off when polishing the contact surfaces or one would remove the case hardening and initiate fast wear." Furthermore, seems that years ago the hammers were showing case hardening colors. However, I am old and may not be remembering correctly.

[Bill DeShivs]

dahermit is correct.
Case hardening is used to give a hard surface to an otherwise ductile steel/iron part. If hammers were hardened all the way through, they would break often from impact.
I have a brand new (3-4 years old) model 37. The hammer and trigger are case hardened.
I have an M&P from the 1940s and the hammer and trigger are color case hardened-as is the trigger on my 3rd model; Safety Hammerless from the 1940s.

[4V50 Gary]

Earlier S&W hammers were case hardened. We were warned (back in '84) not to stone the surface too much lest we go past the case hardening.

As to the pushoff, that's generally because the single action notch on the hammer failing to hold. Worn SA notch on hammer will cause this. Open her up and take a look-see.