Cannot tune K38 below 7lb.

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dahermit

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I have a S&W K38 circa 1959 that I cannot "tune" for a lighter than seven pound double action pull. I have several other S&W double-actions that I can get down to a six pound pull and have reliable ignition with Federal primers. However, they are four inch guns whereas the K38 is a six inch and I want to keep the extra sighting radius advantage. Keep in mind that this is a "fun gun" that is dedicated to shooting steel bowling pins at fifty feet...it is used for nothing else. If I cannot get it down to six pounds, I may as well give up on this gun for my chosen game.
Notes: I have done all the polishing, etc. I need to find why and "fix" the gun requires such a heavy (yes I have aftermarket spring kits galore), mainspring to keep it from misfiring. I know my primers are seated correctly inasmuch as none of my other K frames are misfiring, even at six pound pulls.
I think what is happening is that the firing pin is striking the angled slot inside the firing pin bushing before it enters the firing pin hole and hits the primer...depleting some of its energy resulting in some light strikes. Layout dye applied to the hammer nose (firing pin) and the inside of the firing pin bushing seem to suggest that is what is happening I can see where the Blue is removed inside the slot, just above the firing pin hole. Also, I have been working with two different hammers and two different lengths of firing pins...light strikes occur with both. That suggests to me that the distance of firing pin noses in regard to the pivot hole in the hammers is NOT the problem. I suspect that the actual posistion of the hammer pin in regard to the hole in the firing pin bushing is a few thousandths off.
That era of K38 had no spring behind the hammer nose. I installed one anyway just to see if the spring would push the firing pin down and avoid striking the bottom of that little slot, but it made no difference whatsoever.
I have checked the hammer for any undue friction and hitting on the frame due to misalighment (shim on either side to straighten its travel), and verified with layout dye on the hammer. I also assembled the gun without the mainspring and rebound slide to verify no undue friction/rubbing by shaking the gun for and aft to see if the hammer would freely flop back and forth.
To those knowledgeable with S&W double-actions: Am I likely correct as to the nature problem...do I seem to be on the right track? Is there a remedy other than going to a different gun?
This is a gunsmithing question only...please do not suggest things like, "...exercise your hand so you can pull a heavier trigger...", or, " why do you need a pull that light?", etc. Please stay on topic.
 
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Obviously, if there's actually something wrong it needs correction or it's probably just going to get worse.
But to feel the difference between a 7 and 6 lb trigger might be drag and friction, more so than springs.
It sounds like you are going about it the right way, though.
If it's what you suspect, then trying to set things straight (literally) will require a very light touch.

If it's not worth the risk of doing more harm than good, and you want to continue using this particular revolver, maybe changing your focus might be a better choice.
I've found that the way to deal with a less than ideal gun during competition has been to focus on the results and not the tool.
Thinking about the gun instead of the hits can aggravate a relatively minor short coming.
Kind of Zen like, but has worked for me.
Just a thought.

P.S.
As a last resort, if you indeed want to keep using this revolver no matter what, there's always the choice of sending it to a competition level gunsmith.
There's a reason they charge so much as compared to a regular ole' smith.
 
If it's not worth the risk of doing more harm than good, and you want to continue using this particular revolver, maybe changing your focus might be a better choice.
I've found that the way to deal with a less than ideal gun during competition has been to focus on the results and not the tool.
Thinking about the gun instead of the hits can aggravate a relatively minor short coming.
Kind of Zen like, but has worked for me.
Just a thought.
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I thought that I made it clear in the original post: "This is a gunsmithing question only..."
P.S.
As a last resort, if you indeed want to keep using this revolver no matter what, there's always the choice of sending it to a competition level gunsmith.
There's a reason they charge so much as compared to a regular ole' smith.
Click to expand...
Unless a "competition level gunsmith" is sitting on some dark hidden secret thing that no one else knows about (or can perform something magic that is beyond the realm of physics), he is not likely to be able to do anything that would fix the problem.
 
I'd be very surprised if any one could tell the difference between a 7 and a 6 pound trigger.
However, it's more likely to be the hammer itself being a tick off straight. Can you see it touching the sides of the frame? The layout dye seems to indicate it is. Seems to me the actual fp is much smaller than the slot.
The trigger on the M19 I had before the GP had all the innards polished smooth and flat and shiney. DA trigger was unbelievably smooth. Smooth also being more important than the pull weight. It'd never be smooth if the hammer touches anything but the primer.
 
Unless a "competition level gunsmith" is sitting on some dark hidden secret thing that no one else knows about (or can perform something magic that is beyond the realm of physics), he is not likely to be able to do anything that would fix the problem.
Click to expand...

But I bet he would be a better bet than guidance from anonymous strangers on an internet forum. Don't get me wrong, I love forums. I've learned to do everything from replace a timing belt on a Ford to reaming chamber headspace on a rifle. With that being said, you must separate the wheat from the chafe with advice received on a forum.

I'm not knocking the fact that you asked the question here. I'm sure someone may read your description and have an "ah-ha" moment or have personally encountered it before and they know the fix. I understand what you're talking about, but have no previous encounters nor any "ah-ha's" for you. I guess what I'm really taken aback by is the assertation that a well known, premium gun smith is just as clueless as internet forum dwellers...
 
It is my understanding that double action revolvers with very light triggers almost always used lightened hammers. Have you tried using a lighter hammer or making lightening cuts on one of the hammers your are using?

You are probably aware of lightened hammers, but I will still discuss it briefly. Many people expect that a lighter hammer will require a stronger spring, but this is actually not the case. When you use a lighter hammer, the mainspring strength remains the same. And the same strength spring acting against a hammer with less mass causes a lighter hammer to move with greater velocity. And since energy is mass times the velocity squared, a lighter hammer will typically have more energy.

Similarly, Smith & Wesson target hammers are known to be enough heavier than standard hammers that they require a stronger mainspring, and people tuning revolvers typically avoid them.

Other than these thoughts about hammer weight, it sounds like you have covered all the common issues. Hammer friction and firing pin issues are the primary causes of light strikes, and it sounds like you have done a thorough investigation of those issues. Also, are your firing pin strikes dead center? Primers are less sensitive if they are struck off center.

If you are interested in more info about lightened hammers, you could google for retired gunsmith Mike Carmoney. He is well known for his work with hammers, and light hammers are sometimes called "Carmonized." Here is a thread about his work.

http://forums.brianenos.com/index.php?/topic/107539-questions-on-hammer-bobbing/

I hope some of this might be of help.
 
I'd be very surprised if any one could tell the difference between a 7 and a 6 pound trigger.
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I can tell and my trigger pull gage can also...did you think I was guessing?


However, it's more likely to be the hammer itself being a tick off straight. Can you see it touching the sides of the frame? The layout dye seems to indicate it is.
Click to expand...
Hammer is straight and has a shim on either side to keep it centered. Where did you get the idea that the layout dye indicates that it is touching the sides of the frame...I never said that.
 
I'm not knocking the fact that you asked the question here. I'm sure someone may read your description and have an "ah-ha" moment or have personally encountered it before and they know the fix. I understand what you're talking about, but have no previous encounters nor any "ah-ha's" for you. I guess what I'm really taken aback by is the assertation that a well known, premium gun smith is just as clueless as internet forum dwellers...
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Never asserted that at all, I merely pointed out that sending it to a famous gunsmith was not a guarantee. And, as the clockwork of a S&W double action is not all that complicated that none other than a well known gunsmith could figure it out.
 
It is my understanding that double action revolvers with very light triggers almost always used lightened hammers. Have you tried using a lighter hammer or making lightening cuts on one of the hammers your are using?

You are probably aware of lightened hammers, but I will still discuss it briefly. Many people expect that a lighter hammer will require a stronger spring, but this is actually not the case. When you use a lighter hammer, the mainspring strength remains the same. And the same strength spring acting against a hammer with less mass causes a lighter hammer to move with greater velocity. And since energy is mass times the velocity squared, a lighter hammer will typically have more energy.

Similarly, Smith & Wesson target hammers are known to be enough heavier than standard hammers that they require a stronger mainspring, and people tuning revolvers typically avoid them.

Other than these thoughts about hammer weight, it sounds like you have covered all the common issues. Hammer friction and firing pin issues are the primary causes of light strikes, and it sounds like you have done a thorough investigation of those issues. Also, are your firing pin strikes dead center? Primers are less sensitive if they are struck off center.

If you are interested in more info about lightened hammers, you could google for retired gunsmith Mike Carmoney. He is well known for his work with hammers, and light hammers are sometimes called "Carmonized." Here is a thread about his work.
Click to expand...
I am well aware of lightened hammers, have tried one of those (I have a lot of spare parts) in the K38 also to no avail...still light strikes. I did not bring up lighter hammer because there are many who think that lightning the hammer causes light strikes (like one of the first posters), and I did not want to have arguments over that issue in this thread. Several of my other S&W's sport lightened, spurless hammers.
 
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But I bet he would be a better bet than guidance from anonymous strangers on an internet forum.
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Are there no real gunsmiths on here? I was under the impression that there was. Beside that, I am old and wise enough interpret suggestions from those who post here..."guidance", is your choice of words, not mine it is not all that hard to separate the wheat from the chaff.
 
But I bet he would be a better bet than guidance from anonymous strangers on an internet forum. Don't get me wrong, I love forums. I've learned to do everything from replace a timing belt on a Ford to reaming chamber headspace on a rifle. With that being said, you must separate the wheat from the chafe with advice received on a forum.
I'm not knocking the fact that you asked the question here. I'm sure someone may read your description and have an "ah-ha" moment or have personally encountered it before and they know the fix. I understand what you're talking about, but have no previous encounters nor any "ah-ha's" for you. I guess what I'm really taken aback by is the assertation that a well known, premium gun smith is just as clueless as internet forum dwellers...
Click to expand...
I tried to be as clear as possible: This is a gunsmithing question only...please do not suggest things like, "...exercise your hand so you can pull a heavier trigger...", or, " why do you need a pull that light?", etc. Please stay on topic.
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I come here for information (otherwise I would have posted my question in the "general" section), please save any unsolicited comments for your facebook friends.
 
I come here for information (otherwise I would have posted my question in the "general" section), please save any unsolicited comments for your facebook friends.
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The very nature of starting a thread asking a question on an internet forum is to solicit comments. My comment is you are silly to think that a well respected and known gunsmith with a reputation working on Smith revolvers can't help you. Much less "magic and pixie dust" involved with that route than praying the 30 year head craftsman at S&W custom shop will join TFL today and give you the obvious solution. If you have tuned numerous S&W revolvers to sub 7lbs, then you probably have a leg up on 99% of TFL members. If you cant solve the problem, the obvious escalation would be a master who does it for a living.

Yes I do intend to sound like a smart ass, and I usually don't do that. At any rate, I do wish you the best of luck in solving your problem. And I am sincere.
 
The very nature of starting a thread asking a question on an internet forum is to solicit comments. My comment is you are silly to think that a well respected and known gunsmith with a reputation working on Smith revolvers can't help you. Much less "magic and pixie dust" involved with that route than praying the 30 year head craftsman at S&W custom shop will join TFL today and give you the obvious solution. If you have tuned numerous S&W revolvers to sub 7lbs, then you probably have a leg up on 99% of TFL members. If you cant solve the problem, the obvious escalation would be a master who does it for a living.

Yes I do intend to sound like a smart ass, and I usually don't do that. At any rate, I do wish you the best of luck in solving your problem. And I am sincere.
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Evidently you did not understand that I did not not want other than "gunsmithing answers" only when I posted this: " Please stay on topic." I thought I made it perfectly clear that I did not want any comments outside the realm of that request. Why you feel you must continue to make them is a mystery to me.
I do not come here to socialize, or make lifelong friends...I am only interested in information. I care nothing for your opinion on motives or anything else.
Besides that, where have you ever seen the word "silly" used where it was not meant as an insult? Rhetorical, please do not answer.
 
Check firing pin protrusion and end shake.
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I don't have a good way to check firing pin protrusion...I could try with a set of feeler gages but have no faith in that method. As for end shake, it was within specs, but I shimmed to .002 to the rear anyway just to see if it made a differance...it did not.
 
"Why not just send to a competition gunsmith?"

Because it makes no economic sense. It would logically cost several hundred dollars for a celebrated gunsmith to deal with it, but at the same time it would not make my 1959 K38 any more valuable than what I paid for it. In my case, I am not a competitor...I shoot for my own satisfaction on my own range and am 73 years old. The money spent on a high-dollar gunsmith makes little sense for someone in my position. What does make sense, if I cannot find a remedy, is to just sell the gun and buy another used one...I have seen one for sale on one of the auction site currently. In doing such, I would break about even, and then I could work on the "new one" with what I would expect better success than this one. In all, I look forward to working on S&W double-actions...I am retired and that is how I like to spend my time.

Nevertheless, I never asked for any such suggestion and actually did my best at the end of my original post to deter such suggestions...but there are always those who just cannot get the message.
 
Dahermit, you don't get to make the forum rules. While you certainly can request specific things in a thread you start, you can't impose martial law on the thread unless you are a moderator. I have started threads and received replies that were not relevant and even snarky. I didn't see the need to make 3 following posts chastising them and insulting them in various manners. So... Poor form. I'm not here to make friends, or seek approval. You wanted an opinion as to what to do with it. My opinion is keep trying, if you can't get it then no one else here will likely be any help if you have tuned a number of S&W revolvers as well as you say you have. The only other option is a good gunsmith, preferably a black magic practicing one with hidden knowledge of physics. Those are your words, just so you know.

At any rate, if the internal workings of a smith are so simple, surely you have figured it out by now and no longer require assistance. If you haven't, your best chance may be a gunsmith who specializes in smith revolvers. Or, sell it if its the most economical sense. Finally, "silly" does not always, or even frequently, constitute an insult. If you took it as that, that's exactly what happened... Offense was taken, not given.

And, please quote me in the following 4 or 5 posts while you make specific points. I will then reply again to give you more fodder to quote for the next 3 days. Politely, but I'll be here none the less.
 
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