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First tune-up: Charter Arms 38 Undercover

Posted: Thu Aug 04, 2016 3:58 am
by BadDog
My mother has a 38 Undercover she bought some 45 years ago. I knew she had it, but that's about it. Was going shooting, prevailed upon her that EVERYONE who owns a gun for self defense must spend some time shooing it. So we bought her a box of FMJ and took here with use when we (the me and my kids mainly) went shooting. She got some experience on a wide range of guns, though had not interest in any of the large bores or shotguns, though in the surprise turn around of the day she did really enjoy my customized M17 with bipod and Eotec holo-scope.

Anyway, she couldn't shoot her gun to save he life, quite literally. So I tried it to see what the problem might be, and the gun was beyond awful. Ergonomically it was maybe a 1 out of 10 with a tiny roundish handle making it impossible to keep the gun from swinging while DRAGGING and hauling on the trigger. Doulble action was all but unusable even for me, much less her weaker arthritic hands. She could shoot my SP101 357 Mag (with 38s for her) with ease and good accuracy. Even in single action it was awful. Very hard pull, and no way to guess when it might break and send one down range. I looked for a better quality gun (she really wanted an SP101 like mine) but with current politics, policies, fears, and resulting prices that's just not gonna happen. So I offered to try to give it a tuneup. I'm not a gun smith, but wanted to get into it for some time, had read up in the past, and did lots of new reading trying to focus on the 38 Undercover.

Pretty simple gun all around, but when disassembled it was clear what the problem was. Everything was SO rough, it looked like the inside of lots of modern low budget chinese tools. What you can see isn't mad, anything covered, very rough. So I polished and deburred everything, paying particular attention to the critical surfaces, angles and edges. Most work was done with a very fine diamond lap and a modelers "smooth file" made to sue with super fine sand paper. The difference was nothing less than astounding. Single action is now on par with my SP101 but with a higher spring pressure. But nice, crisp, and completely predictable with no take-up at all once engaged. Double action is also much improved and quite functional now with no tendency to failure or any sort of issue normally resulting from a bad tune-up. Still some drift using dual action from the MASSIVE spring that that was put int to make it reliably work with the rough ground/machined parts inside, but predictable and controlable now without working our way through 3 separate staging "stops"(?) befoer while getting the trigger back and then at unpredictable points feeling the trigger let go. I've shot raggedy non-maintained "truck guns" (bounced around under the seat of a truck for 30 years without any attention) that worked better when finally shot!

Very proud of my first tune up. Thta gun went from something I wouldn't shoot and would feel guilty selling at fire sale prices to something I would absolutely carry without concern (if ever carried 38 Spl).

As for the grips, I love Hogues, but can't find any for the Undercover, even called the office. I don't like packmayr as well, but they have a bobbed "rubber" grip that provides some depth and covers the back strap that looks like it may work well, but I want to put my hands on one before ordering..

But I have 2 questions.

1) What's the best option to lighten the spring? I think it could now go down a good 30% easily without misfires, but there are no spring kits. I'm guessing I can buy generic springs, but what do I look for? I'm afraid I not only do not know sources, but I also don't know how to determine the characteristics of this one, and identify a good candidate. I thought I might get 3 or so over a range to test. She's happy as it is, but I can tell with her arthritic hands, the pull is still just too high. Modifying this spring seems risky and a one way srreet, and making one doesn't fill me with confidence either since it simply MUST work if the time comes.

2) There is a little sort of half cheese-head screw right below the back of the cylinder. It look like you took a cheese head screw and cut off one lobe to the slot leaving a half moon head. I did not remove the trigger mechanism, from what I read very little to be gained in there and very fiddly to get back right. So not sure what that pin does, but now when loaded with Hornady self defense rounds fully seated, with the cylinder ejected and down on the stop (or just above), the shell rims hit the half-head. Iv'e tried resenting the shells, clocking the half-head for max clearance, looked for where maybe I missed a shim or something, I can't find anything. Seems fully functional, but i din't remember id doing that before. Any ideas on what is going on there?

Re: First tune-up: Charter Arms 38 Undercover

Posted: Thu Aug 04, 2016 7:37 am
by BadDog
Shesh, I should have looked this up before. Apparently it's called the Cylinder Stop Stud, and is supposed to assist in ejecting shells. But all I can see it doing is preventing the cylinder from being spun freely when fully open with shells inserted. I'm missing something critical here...

This gun is visually almost identical to her's, except her grip is, if you can believe it, even more like something cut from a broom handle. Near round and with no checkering, so the gun want's to wag if you don't have a good grip, and it's so small even my mother can't really grip it well, and it SURE doesn't fit my hand. Anyway, you can clearly see the cylinder stop pin in this image just below the back of the cylinder and above the trigger. It was not removed when i did the tuneup.


Re: First tune-up: Charter Arms 38 Undercover

Posted: Fri Aug 05, 2016 12:22 am
by Rolland
Before doing any spring work, if the trigger face has ridges on the face polish it smooth and round it slightly so no sharp edges. It will make a world of difference on how smooth the action works. I use Cratex rubber wheels and polish to a mirror finish. Then you can work on springs.

Re: First tune-up: Charter Arms 38 Undercover

Posted: Fri Aug 05, 2016 2:48 am
by BadDog
I've already done that (or similar as applicable) throughout the entire mechanism except the trigger itself. Everything I read indicated that on those guns there was little or now discernible difference in feel (at least for the non-sophihsticated shooter like us) working the trigger group or not, and that the trigger group with all its little pieces was a pain for the neophyte with substantial risk of permanent damage (or lost parts). So I left that alone. But the trigger face itself as well as the transfer bar/slide had clear striations from machine work (coarse grinding it appears). There was also evidence of self polish along the edge indicating that the faces were not in plane (and no, it wasn't riding on a burr). With various magnification and careful use of the laps I was able to remove almost all the marks, and get it contacting across the full surface on the transfer bar as it slides up in the frame. I did clean up the trigger face itself, but since all it does it hit the transfer bar, I wasn't overly concerned bout it, though I did dress the edges a tiny bit which before had noticeable burs. Anyway, mechanically, this thing is really working slick now, especially in single action, couldn't ask for better without going premium and then it wouldn't compare bad. Double action was virtually non-functional when we first took it out. But it now works well without the previous staging/snagging along the way with the final trip of the trigger requiring almost 2 hands and invariably drawing you off target. Now it's quite smooth all the way from start to finish, with a predictable little catch just as a tiny bit more releases the trigger. Maybe not a perfect trigger in many folks book, but the improvement is fantastic and very much good enough for us.

All that said, the shear force required to haul that trigger back with the stock spring is likely better measured in pounds not ounces. My mother can now shoot it double action, should couldn't before. But it does take a significant effort even for me, and I would like it to be at least a bit easier on her so that she doesn't shy away from shooting with us to gain some competence (and hopefully never needs it for real). As a test I watched here dry fire it rapidly 10 times in a row (twice the 5 shot cylinder) while staying roughly on a hypothetical target. She did it and quite well I would say, but she did say that it made her finger start hurting.

For what little I know, there is nothing more to do that will provide a high return on investment in the real world other than reducing the main spring tension. I don't even want to get close to the point of worrying about having light strikes and I'm not looking to find the ultimate, I just want my mother to have something she enjoys shooting without paying what a good gun runs these days (she simply can't afford it). But if I can't find a softer spring, frankly it will be ok. I'm gifting her a new set of the snub carry pachmayr grips, and those should provide enough control to make the spring feel a lot softer anyway...

Re: First tune-up: Charter Arms 38 Undercover

Posted: Sat Aug 06, 2016 12:54 am
by BadDog
I just realized (remembered) that this is a very slow moving forum. I had another forum that someone recommended in the past, friendly to newbies, and I liked it well so added it to my favorites. I actually tried it before this one, but it looks like it's now defunct.

I really expected this would be a pretty quick resolution on this one. CA is known to have stupid heavy triggers to make up for poor fit-n-finish yet still work reliably. So assuming lots have done the simple finish work I've done, I expected there to either be a (possibly discontinued) spring selection kit. Or failing that, details captured somewhere that it's a [however you specify spring details] and you can find lighter springs of otherwise matching specs by [whatever you do]. I even had faint hope someone had bought a spring set and re-sprung one to suit their desires some time back and might have the extras to sell (even if they used the exact spring I would want, just a bit better is all I really want for her). But maybe all those guess about how such things might work out are just pipe dreams. I don't know what I don't know...

Anyway, any suggestions on where I might get more information along these lines? Anything might prove valuable as I have no idea how to begin tracking down spring replacements at this point. I've got probably a thousand springs of all sizes in my shop and have often changed/modified/whatever among them to make things work. But nothing close to the right size and specs, and no idea how to proceed. Just buying her an SP100 or small J frame S&W is looking better and better, until I look again at what even fairly rough examples bring these days. :cry:

Re: First tune-up: Charter Arms 38 Undercover

Posted: Sat Aug 06, 2016 2:54 am
by 10KPete
The cylinder stop keeps the cylinder from falling out when it's open. Otherwise the ejector star and spring take the
load and they're not designed for that.

For springs, I've always kept every spring that came to hand, just in case. I've also bought the stock lengths from
Brownells and have a lot of that. When I need a spring I go to the stash and find something and make it work. A lighter wire in the required diameter for example. Or a shorter or longer one. Or whatever. There's no magic in
springs. Just find one that will do the job and fit it. Failing that I've wound a lot of customs out of piano wire.

But understand that you need to know the mechanism. I've seen a lot of Smiths where a "gunsmith" has worked the
hammer spring or the anchor screw to lighten the trigger. Wrong! It's the coil spring in the square housing that is
responsible for most of the trigger weight! And then if they do figure that out, they cut coils off. Wrong again! It's the wire diameter that determines the spring weight for a given spring diameter. Should have taken the time to find
the same size spring in lighter wire...

Gunsmiths make most of their money fixing other "gunsmiths" ignorance.


Re: First tune-up: Charter Arms 38 Undercover

Posted: Sat Aug 06, 2016 8:58 pm
by SteveM
10KPete wrote:And then if they do figure that out, they cut coils off. Wrong again! It's the wire diameter that determines the spring weight for a given spring diameter. Should have taken the time to find the same size spring in lighter wire...
It's like the kids around here that cut their springs to lower the car and end up screwing up the spring rates (and the difference in spring rates front to rear) and end up with a car that pitches front to back when they hit a bump in the road.


Re: First tune-up: Charter Arms 38 Undercover

Posted: Sun Aug 07, 2016 10:54 am
by BadDog
Cylinder Stop: Once I found the better parts drawing scans and found the name, then did a little reading, it's basic purpose no longer has me confused. The problem is that before I stripped it to the frame (other than trigger), I believe the cylinder with cartridges spun freely when full open. Now, with the same cartridges, smooth rotation movement hangs on the rim of each cartridge. I don't believe that is normal, and I can find no means of adjusting/correcting, so can anyone tell me my mistake?

Main Spring: Pete, I'm the same as you, I've got bins and boxes of springs. Every likely organ donor that expires in my possession, should time, timing, dealings and health allow have been disassembled for springs, wires, plugs, clamps, adjustable feed, motors, controls, anything and everything that is not either to bulky or too specialized/odd to ever likely find a use goes into one of my many bins. However, in this case, I do not have a spring that is close enough to acceptable to work with (at least not that I've found yet). And if I were not already well versed in basic spring mechanics before that, my time designing the 4 link coil suspension of my rock crawler would have quickly filled in the blanks.

So, given the lack of "spring kits", my suspicion is/was that I would need to buy generic springs from somewhere, perhaps Brownells. I've got a Mit pin mike that should give me an accurate measure of the wire diameter (don't want to ruin it), which would be the first step. But after that, in this world of gun main springs, how does one proceed with determining suitable springs to order to get desired results? I'm not interested in adjusting anything except to substantially reduce the force necessary to operate the gun in dual action mode without in any way making the gun unreliable. All other functions are completely acceptable to both her (and me). And that goal would appear to indicate focusing pretty much solely on the main spring. Reading before starting this project read again and again that CA (of that era at least) used a heavy spring to make sure it worked reliably without requiring time necessary to properly finish hidden parts and mechanism and thus improve profits (obviously the generic fore bearers of all managers today). All indications are that I've addressed the internal fits and finishes that required the heavy spring (and they were quite bad). But how DOES one go about taking the original and determining where to start with replacements? I would like to guess as little as possible without spending (wasting?) too terrible much time calculating/estimating endless minutia? I know my tuneup isn't perfection, and even if it were, I would still need to worry about going too light resulting in light strikes and reducing reliability of the weapon. This is where I need some helpful guidance, even (I suppose) if it is simply that "they are cheap, just guess at a handful of options, buy a few boxes of shells, and try till it works like you want it to."

Re: First tune-up: Charter Arms 38 Undercover

Posted: Sun Aug 07, 2016 12:34 pm
by hammermill
my sugestions are to buy a few extra spring sets, play with legenth, temper and even make some of smaller diameter spring wire and learn to temper springs. consider it a educational odessy.

Re: First tune-up: Charter Arms 38 Undercover

Posted: Sun Aug 07, 2016 2:31 pm
by BadDog
As far as buying a selection and experimenting, I was afraid it might go that way.

At various times I've read up on making springs and depending on your starting points and many other things, the options and process can vary greatly. I may one day venture into that odyssey perhaps even as far as doing my own hardening tempering, but I'm highly unlikely to be doing so for the first time on the main spring for my mother's personal protection carry gun. :D

Re: First tune-up: Charter Arms 38 Undercover

Posted: Mon Mar 20, 2017 10:52 am
by PeteH
Coming in late on this one... I believe you can get model-specific springs from Wolff Springs -- IIRC, they sell heavy and light springs. Not expensive, either -- the shipping cost probably will exceed the parts.

Another thing to check out is the headspace (between the rear of the cartridge and the frame).

I've got a Charter from about 1968, and the internal finish is just fine; and the thing works very well, although I recently had several misfires when shooting imported target ammo. No problem with a box of domestic stuff, so I'm blaming it on hard primers.

Re: First tune-up: Charter Arms 38 Undercover

Posted: Mon Mar 20, 2017 11:56 am
by BadDog
Thanks for the update, I'll keep that resource in my back pocket for future reference.

In the way of a general update, the gun has been working flawlessly since my polish job, and has been good enough for her to not shy away from shooting it, as long as we don't go through more than one cylinder at a time without breaks (or with cold hands). I may revisit the gun in the future, but right now I'm just happy that I could make such a big improvement in the gun, and not do something to make it unreliable.

She also loves the new grips, which do a big part to make the gun more functional for her. And by making the gun more steady in her grip, the heavy trigger pull has not affected her nearly like it did with the OEM grips.