Question about 642 internals

[JackGordon]

I read recently (I think here at the forum) that the 442 and 642, since they have shrouded hammers, forego the hammer block. The thinking seems to be that, since nothing can touch the hammer, there's no need to block it from the firing pin. I have seen on several sales sites, though, that the Ruger LCR, even with the shrouded hammer, is equipped with their transfer bar for safety. My question is why S&W didn't just retain the hammer block in case the Airweight guns are dropped on their nose? Wouldn't that block tend to prevent an AD in that case?

 

[Alk8944]

Because the hammer block in the "Centennial" style frame is superfluous. Deleting it saves several machining steps and eliminates the pin in the rebound slide. There is absolutely no possibility of the revolvers firing if dropped muzzle down!

The Ruger transfer bar performs exactly the opposite function in their guns and the gun will not fire at all if the transfer bar is not installed. They may look similar, but they are not!

 

[armorer951]

The hammer block is not the primary safety in the S&W family of revolvers. The primary safety is the mechanical relationship between the rebound seat on the hammer, and the hammer seat on the rebound slide.

If, in the exposed hammer models, the hammer moves forward for some reason other than the normal pressure on the trigger by the shooter, (for example pushes off, or the gun is dropped while cocked and comes off the bevel of the trigger) both the hammer and the trigger immediately return to their "at rest" positions. Due to the impetus from the rebound spring, the trigger and rebound slide assembly arrive at rest ahead of the hammer, which places the hammer seat (on top of the rebound slide) in position to prevent the hammer from moving past it's "at rest" position, and the hammer nose, or the frame mounted firing pin from entering and passing through the breechface.
Since, by design, the hammer cannot move forward in the prevously stated scenarios on these shrouded, double action models, the hammer block is, as the previous poster stated most succinctly, "superfluous".

 

[kaaskop49]

^^^^what he said. Now, if S&W would do a little more fitting (or ANY fitting, for that matter!) between the hand and ratchet on their Centennials... All the recent mfgr 442, 642, 340 models (the 442 PC "Chattanooga" pintos especially) seem lacking in this regard. I should know.

Kaaskop49
Shield #5103

 

[AZretired]

Not sure what you mean by recent vintage but my 642-1 of 2014 vintage has excellent f&f as well as a smooth trigger pull.

Sent from my XT1254 using Tapatalk

 

[ContinentalOp]

^^^^what he said. Now, if S&W would do a little more fitting (or ANY fitting, for that matter!) between the hand and ratchet on their Centennials... All the recent mfgr 442, 642, 340 models (the 442 PC "Chattanooga" pintos especially) seem lacking in this regard. I should know.

I believe I have that issue with my 642-1. When pulling the trigger, I will sometimes get a very slight "hitch" towards the end of the pull. It's a different sensation than "staging," if that makes sense. It has gotten better with use. It hasn't been a big issue, especially when firing quickly, and has had no impact on reliability or accuracy, so I haven't bothered with contacting S&W about it. But I have been considering having a trigger job done and will bring it up to the gunsmith if that should ever happen.

 

[kaaskop49]

Not sure what you mean by recent vintage but my 642-1 of 2014 vintage has excellent f&f as well as a smooth trigger pull.

Sent from my XT1254 using Tapatalk

...And that's the way it should be, but too often is not. A DA comparison of my slick 637 PC 'Wyatt' of 2013 and recent Centennials makes me shake my head sadly. Glad your 642 is well-made, it's a carry gun, after all! Be safe, partner. Check 6.

Kaaskop49
Shield #5103

 

[JAREDSHS]

just for the record ,my new 638, which was put together sometime early this year(2017) appears nicely put together, has .006 gap at cylinder face to forcing cone, tight lockup with trigger held back, very slight wiggle with trigger at rest, all aspects of the barrel are perfect, almost reminds me of the way S&W put them together years ago. I do not own a trigger pull gauge, but the pull is firm and very smooth. I am proud.

 

[JDinAZ]

I believe I have that issue with my 642-1. When pulling the trigger, I will sometimes get a very slight "hitch" towards the end of the pull. It's a different sensation than "staging," if that makes sense. It has gotten better with use. It hasn't been a big issue, especially when firing quickly, and has had no impact on reliability or accuracy, so I haven't bothered with contacting S&W about it. But I have been considering having a trigger job done and will bring it up to the gunsmith if that should ever happen.

I had a similar hitch in my 329PD. Never bothered me enough to investigate or do anything about it. Then one day while I was putting mine back together while working on developing my Lock Delete part set I left the transfer bar out and the hitch was gone. So I threw that bar in the bag with the internal lock parts and in the ol box it went. Now mines pretty dog gone smooth and best part is that bar can't rattle either which did kind of drive me nuts. I figure they never had em for 150yrs so I don't need one now.

 

[kaaskop49]

I had a similar hitch in my 329PD. Never bothered me enough to investigate or do anything about it. Then one day while I was putting mine back together while working on developing my Lock Delete part set I left the transfer bar out and the hitch was gone. So I threw that bar in the bag with the internal lock parts and in the ol box it went. Now mines pretty dog gone smooth and best part is that bar can't rattle either which did kind of drive me nuts. I figure they never had em for 150yrs so I don't need one now.

With respect, that transfer bar is there for safety reasons. IIRC, a dropped revolver (before the transfer bar development) in WW II caused a casualty to a U.S. service member. I would not leave it out of the mechanism under any circumstances. Some more experienced members may chime in more knowledgeably.

Kaaskop49
Shield #5103

 

[armorer951]

Well, it's actually not a "tansfer bar". It's called the hammer block. It does serve a necessary and important "passive" safety function.

It may be "pretty dog gone smooth", but removing a hammer block creates an unsafe condition, and altering or removing any safety from a firearm shifts much of the liability in terms of integrity of the mechanism, from the company to the user. (or the owner or gunsmith who modified the gun)

If a hammer block interferes with the action to the point where the function is degraded, then there is something wrong with the revolver's internals, or the hammer block itself is defective.

 

[JDinAZ]

Some folks like the extra gizmos inside. Some such as myself do not. I have no problem taking responsibility for what I do to my guns so liability being pushed back on Smith never crosses my mind.

They make a very nice wheel gun nowadays in many configurations that were never available prior to the new manufacturing methods which is why I carry the 329PD..

Removing it makes it about the same as having a pre hammer block Smith gun. So I guess I don't see where that's deemed unsafe.

By that logic does that mean you are telling us that all Smith's before the hammer block are unsafe. That's kinda what that statement translates to.

Now if you're gonna drop it all the time then that's unsafe no matter what the configuration

 

[armorer951]

You are indeed free to remove or alter the internal safeties built into your revolver. However, and I know I'm preacing to the choir here.....it is the responsibility of all gun owners to carefully consider the gun safety implications of their actions before they make any such careless alteration. This would especially be true of any owner action that would alter or otherwise compromise the factory designed and installed passive and/or active safety devices in any firearm. These crucial parts are not "extra gizmos".

We all have to think of not only our own safety, but the safety of others around us. When we are shooting, we are indeed literally responsible for their safety in terms of the care and handling of our firearms.

The bottom line is this: civil monitary judgement is one thing......but to carelessly modify a factory design could result in someone's accidental injury or death.

 

[JDinAZ]

Armorer951 I see we both agree that folks are free to do what they like. And they should take into consideration all aspects before they make a decision.

Leaving that part out is no more dangerous than buying a pre gizmo gun though. Since they weren't in there in all the older guns.

Nor is it blatently careless to do so. No more so than having a trigger job done on a ccw gun when you go into court to defend yourself and the Prosecutor tries to monsterize you since you made that carry gun more deadly due to a hare trigger. Many very careful folks have done it and nothing happens. They know its not in there and care for their loaded new style production revolver same as their older production ones.

I guess I am confused how that part not being in could cause this death you describe above though.

Maybe its the Marine Corps in me where 20+ years ago they beat into our heads that there is no such thing as an accidental discharge. Its negligent discharge.

And yes sir I would agree with you wholeheartedly that anyone anywhere at anytime that creates a negligent discharge situation is a danger to themselves and others.

I'm not looking to stir the pot. There is always two sides to every coin. You stated your position. I stated mine.

 

[armorer951]

Sir....by removing the revolver's hammer block, a factory designed and installed passive safety, you have literally created the very neglegent discharge potential you seek to avoid.

I'm sorry, but as a S&W trained armorer, I'm going to have to strongly disagree with your position on this one. There just isn't any wiggle room when it comes to safety, especially when dealing with firearms.

 

[JDinAZ]

Yes sir I can completely see your side of the fence by the Armorer manual. And I cannot fault you for that. Not one bit. You are concerned with safety. As are we all.

I still do not understand how that will create a negligent discharge.

Where I get confused is that part did not exist at all for year and years, I'm sure if a historian stops by maybe he will throw in when the first smith wheel gun was made since I've never looked into that.

Folks still carry and shoot Smith's daily that never had one. (Pre guns)

Are they too creating a negligent discharge situation by carrying their factory gun that never had this in it to begin with. Same as I carry mine with it removed.

 

[JackGordon]

The hammer block is not the primary safety in the S&W family of revolvers. The primary safety is the mechanical relationship between the rebound seat on the hammer, and the hammer seat on the rebound slide.

If, in the exposed hammer models, the hammer moves forward for some reason other than the normal pressure on the trigger by the shooter, (for example pushes off, or the gun is dropped while cocked and comes off the bevel of the trigger) both the hammer and the trigger immediately return to their "at rest" positions. Due to the impetus from the rebound spring, the trigger and rebound slide assembly arrive at rest ahead of the hammer, which places the hammer seat (on top of the rebound slide) in position to prevent the hammer from moving past it's "at rest" position, and the hammer nose, or the frame mounted firing pin from entering and passing through the breechface.
Since, by design, the hammer cannot move forward in the prevously stated scenarios on these shrouded, double action models, the hammer block is, as the previous poster stated most succinctly, "superfluous".

Thank you very much for the reply (I'm new to the forum and still a little confused about finding posts that reply to my questions, so I'm late with my thanks here.) I defer to your (clearly) superior knowledge of S&W guns and will continue to carry my 642 with the confidence that it is an especially safe firearm. Thanks again.

 

[photoman]

Yes sir I can completely see your side of the fence by the Armorer manual. And I cannot fault you for that. Not one bit. You are concerned with safety. As are we all.

I still do not understand how that will create a negligent discharge.

Where I get confused is that part did not exist at all for year and years, I'm sure if a historian stops by maybe he will throw in when the first smith wheel gun was made since I've never looked into that.

Folks still carry and shoot Smith's daily that never had one. (Pre guns)

Are they too creating a negligent discharge situation by carrying their factory gun that never had this in it to begin with. Same as I carry mine with it removed.

The hammer block began during/after World War II if I recall correctly. I dare say there are not many people out there carrying pre-war S&W revolvers for self defense.

Once you understand the mechanics of the hammer block, it's hard to imagine removing it having any noticeable effect on the trigger pull. And seeing how we are all human, and handguns get dropped all the time, it really doesn't make much sense to remove the hammer block.

 

[JDinAZ]

Seems as though you know a decent bit about internals Photoman44. Can you shed some light on armorer951s post for me. Where he stated in collegiate terms that the hammer can't contact the firing pin unless its intentional. Thus it is an unneeded part in his own words.

The hammer block is not the primary safety in the S&W family of revolvers. The primary safety is the mechanical relationship between the rebound seat on the hammer, and the hammer seat on the rebound slide.

If, in the exposed hammer models, the hammer moves forward for some reason other than the normal pressure on the trigger by the shooter, (for example pushes off, or the gun is dropped while cocked and comes off the bevel of the trigger) both the hammer and the trigger immediately return to their "at rest" positions. Due to the impetus from the rebound spring, the trigger and rebound slide assembly arrive at rest ahead of the hammer, which places the hammer seat (on top of the rebound slide) in position to prevent the hammer from moving past it's "at rest" position, and the hammer nose, or the frame mounted firing pin from entering and passing through the breechface.
Since, by design, the hammer cannot move forward in the prevously stated scenarios on these shrouded, double action models, the hammer block is, as the previous poster stated most succinctly, "superfluous".

Clearly armorer951 knows the mechanics of the functions there no doubt about that. Much better than I do about the sear and rebound slide since I have no interest in trigger jobs I've never looked into those parts that deeply to learn the ins and outs of them.


Again where I am confused is in one breath its an un needed part. Then in the next breath I'm getting slammed and being made out to be a dangerous renegade for taking mine out.

Logic does not support these two contradictory statements.

 

[photoman]

With exposed hammer S&W revolvers with no hammer block or a removed hammer block, it is possible to impact the hammer spur in such a way as to cause the gun to discharge. I don't know the exact mechanics of it all but I suspect the impact moves the rebound slide in such a way as to permit the hammer to move forward and discharge the gun.

After watching this animation for a while (scroll down a bit)...

The U.S. Victory Revolver : : C&Rsenal

...you can imagine how dropping the gun could cause the rebound slide to move in a rearward direction, dropping the hammer off of the "hump" on top of the rebound slide and permitting the hammer to move forward and strike the primer.

An interesting side thought... Using a very lightweight rebound spring in a Centennial type gun would make it more likely to discharge if dropped on the back part of the gun. Or at least it seems like it would.