Help identify 629-3 part

[Nraman]

I opened up the plate of my 629-3 to clean, lube and replace the trigger stop rod.
While the frame lay bare, I noticed a vertical channel in the frame with a shuttle looking part that has a horizontal slot. It appears that a pin on the trigger makes the part move up and down. I was planning to check and figure out what it does, unfortunately I had to rush to finish what I was doing and forgot all about it. I don't want to remove the sideplate again just for that. I was hoping somebody can tell me what the part is called and what it does.
I know for a fact that my 686 doesn't have one.

 

[Smith357]

I belive what you are looking at is the "Safety Hammer Block"
part #78 in this schematic

During WWII a sailor dropped his S&W on its hammer, causing it to discharge and kill him, S&W began fitting the
Victory Models in 1944 with a safety hammer block.

 

[Nraman]

No, I am familiar with the hammer block. This is a small part, about .250" long, width about half that and rides up and down in a channel in the frame, not the sideplate.
The trigger has a pin and I had to match the pin in the slot of that part. I also tried the Brownells schematics, couldn't find it.
Lets put it this way, when I pull the trigger, it moves the hammer, the slide, cylinder stop and through the pin on the left side of the trigger, the unidentified part.

 

[Nraman]

I find it strange that my 686 doesn't have that part and that it is not included in any of the schematics.
Is it possible that it is a S&W custom feature for the DX models?
I don't have access to my camera now, as soon as I get it back, I'll take a picture and post it.

 

[Alk8944]

It is the bolt lock and is used only on some magnum N-frame revolvers. It locks the bolt back and keeps it from un-latching the center pin on heavy recoiling magnums.

The bolt, part 22 in the above schematic, is what the thumbpiece is fixed to and pushes the center pin forward to unlatch the cylinder so it can be opened. When shooting heavy loads with heavy-for-caliber bullets the cylinders have been known to unlatch when the gun is fired.

 

[Nraman]

It is the bolt lock and is used only on some magnum N-frame revolvers. It locks the bolt back and keeps it from un-latching the center pin on heavy recoiling magnums.

The bolt, part 22 in the above schematic, is what the thumbpiece is fixed to and pushes the center pin forward to unlatch the cylinder so it can be opened. When shooting heavy loads with heavy-for-caliber bullets the cylinders have been known to unlatch when the gun is fired.

Thank you I appreciate it. Next time I open it I'll be able to see better how the whole thing works.

 

[500 Magnum Nut]

It's a bolt block. It blocks the bolt from push (bouncing) opening the center rod under heavy recoil.
The X frame and N frame magnums have it.

 

[Nraman]

It's a bolt block. It blocks the bolt from push (bouncing) opening the center rod under heavy recoil.
The X frame and N frame magnums have it.[/IMG]

That's the one, great picture, I can see how it would move up and lock the bolt when the trigger is pulled.
Thanks.