PC 627 DA sear cross pin backing out

[seanct]

I have a well used 627 that has a problem.

The cross pin which holds the double action sear to the hammer is working its way out to the point that it hits the side plate.

I assume the pin is held in place by friction against the hammer and the sear moves freely on the pin?

It takes several hammer taps to get the pin back in correct position, but within a few hundred trigger pulls it works itself back out.

At the suggestion of a friend, I tried a dot of green loctite on the pin. This kept the pin in place for about 700ish rounds.

Thoughts?

 

[scooter123]

First question, did you remove the pin to apply the locktite? If you didn't I would suggest that you do that before doing anything else. Locktite needs to be applied to the entire surface to be most effective and the only way to ensure complete wetting is to install a wet pin in a wet hole.

If that doesn't work the next step is to try a brand new pin. It might be just a tick larger and and provide a proper press fit. However, I suspect that's somewhat unlikely.

What is more likely is that the hole for this pin has become egg shaped. Since it's a forged hammer this actually increases the likely hood that you have an egg shaped hole in your hammer. If that is the case, the only option you have is to replace the hammer. BTW, issues such as this are one reason why I prefer the through hardened MIM components.

Since it's quite likely you'll find you need a new hammer I can tell you that you can use a MIM hammer with a Forged trigger, S&W is currently assembling the 625 JM using a flash chromed MIM hammer with a Forged Trigger. Knowing this may make it a bit easier to find a flash chromed hammer for your 627. Just be aware that the MIM hammer uses a different spring stirrup and a different DA sear. If you can find a Hammer Assembly it will come with the DA sear installed. That means that the only other item you may need to purchase is the spring stirrup.

If you want to stay with a Forged hammer I suspect that the only source for this part as a new part will be S&W. In that case IMO you should give S&W a call and see if they will sell you a new hammer.

 

[tomcatt51]

First question, did you remove the pin to apply the locktite? If you didn't I would suggest that you do that before doing anything else. Locktite needs to be applied to the entire surface to be most effective and the only way to ensure complete wetting is to install a wet pin in a wet hole.

Only problem is that this gives you a great opportunity to loctite the sear in place so it won't move.

You have a couple choices without replacing the hammer:

Clean the pin and sear and hammer with acetone, assemble it, and try a drop of 290 (wicking) loctite on the pin ends. It will wick in and may be enough.

Take the pin out, lay it on the anvil part of your vise and flatten the end slightly with a hammer. Re-assemble, flat end goes in last. That usually tightens them up enough.

 

[seanct]

The first time I had moved the pin out for the green loctite and it did hold for about 700 rounds.

The second time I repeated that process I managed to get some leakage into the sear(as predicted by tomcat) and the sear locked up.

That pin is exceptionally hard and small and I initially tried to get a flare on it without success. Your procedure(flattening one end) is much smarter than what I was trying to achieve and I am sure that would have lead to success. Live and learn!

Because I need this gun working correctly I ended up taking it to a local smith yesterday. He said its a fairly common issue and he is fabricating a slightly oversize pin.

 

[TSQUARED]

With an appropriate sized punch very lightly peen the ends of the pin.

 

[seanct]

With an appropriate sized punch very lightly peen the ends of the pin.

Yeah, I know now. I just got a copy of the S&W shop manual and they show the swaging technique used for that pin.

So obvious, but I lacked the experience...