broken trigger stud question

[growr]

So, I posted about my M37 having a broken trigger stud...my real question is...how do they actually break? I cannot see where there is enough torque exerted in pulling the trigger to bend or ultimately break this steel pin, especially when it is all assembled.

Any one shed light on this problem?....I am reading more and more about it...just wondered how it was happening...........Seems like this shows up a bit more often in J frames than K-L-N etc...wonder why?

Thanks Forum members!!

Randy

 

[Muley Gil]

Hard to say. Too much dry firing with the side plate removed? A flaw in the stud during machining? Bent at some point in time?

 

[Hondo44]

Randy,

Your correct, one can not see the exerted pressure (not torque which is rotated pressure) and in fact one can not even imagine it. But if you take the trigger return spring between two fingers and try to compress it, than add the tension of the hammer spring which trigger movement must overcome, it begins to illustrate the pressure on the pin.

That makes me wonder how they don't all break! In all likelihood, the pin was hardened a bit too much making it too brittle.

 

[H Richard]

I believe that some hard knocks on the end of the hammer either cocked or at rest can weaken the stud some. Years of wear contribute. The fact that so few ever break in a tribute to the design.

 

[growr]

Thanks for enlightening me guys....I will keep you all posted as to the disposition of this interesting project. I am hoping my friend that is was a NASA Master Tool & Die Maker will think that this is child's play and have this bad boy up and running again....

I even have the correct replacement stud...

Randy

 

[Hondo44]

My son replaced a broken one in a Mod 43, the alloy 22/32 Kit Gun.

This was a simple repair. The broken off piece of pin left in the blind hole in the frame was not difficult to remove with needle nosed pliers. It appeared to be just a 'snug fit', not a 'slip fit' and not a 'press fit'.
Once the sideplate is installed, the pin is 'captured' so it does not need to be that tight in the hole. You might want to investigate and try it yourself.
If the replacement pin has splines on the end that goes in the hole, it would be a simple 'press in' with a gentle squeeze in a small padded vise. I would not try to drive in because of the lack of control to keep it straight and 90 degrees to the inside surface of the frame.

 

[Mike SC Hunter]

I had one break back in the early 80's in a an almost new 29-2. gun was never dropped/monkeyed with or snapped excessively. Smith replaced it and re-nickeled the frame.
Hondo .......I was under the impression that some were screwed into the frame.........Hence the refinish on mine.

 

[growr]

I looked at it and there just isn't enough to grab with a pair of pliers...will have to be pressed out...or so it looks to me.
But thanks for the suggestion!!

Randy

 

[Hondo44]

I had one break back in the early 80's in a an almost new 29-2. gun was never dropped/monkeyed with or snapped excessively. Smith replaced it and re-nickeled the frame.
Hondo .......I was under the impression that some were screwed into the frame.........Hence the refinish on mine.

Hi Mike,

You may be absolutely correct. Although screwed in pins/studs are not usually finished flat, because the threads show and make a poor seam that plating will not cover. Instead they were left domed.

I can honestly say I don't know that much about trigger pins and try only to share actual experiences like the one I shared with my son.

I do know that S&W constantly makes changes in production techniques that can and do differ depending on the vintage. Early hammer studs were threaded on K frames and changed to a flat polished pressed in stud in the early 1950's for example.

Techniques also differ between frames sizes.

 

[mikepriwer]

All the pre-WW2 K-frames have threaded studs. 1899's and probably 1902's are
like that. Somewhere in the later guns, they peened around the circumference with
a circular ring, making it harder to get out.

Mike Priwer

 

[Muley Gil]

I once repaired an early 1920s 2nd model .44 that had a loose hammer stud. I degreased it, tightened it down, and then peened the edges.

As Mike Priwer stated, the post war revolvers have studs that are pressed into place, then the frame is polished so well you can barely see them. That's why the factory had to renickel Mike, SC Hunter's M29-2.

 

[Hondo44]

I looked at it and there just isn't enough to grab with a pair of pliers...will have to be pressed out...or so it looks to me.
But thanks for the suggestion!!

Randy

So much for my memory, I was thinking it was a blind hole. You obviously can see that it's a 'thru' hole. That means the replacement will need to be polished flat after installation. Tough to do w/o messing up the frame anodizing. You might dome the end of the pin like Smith did before their front sight pins were flat polished. But it can't stick out too far or it'll scribe the cyl.