Question about S&W K-frame actions and triggers

josquin

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I’ve a had a 6” Model 14-3 (.38 Spec.) for a few years and it has the typically smooth and light trigger these are known for. l recently picked up a 6” Model 19-4 (.357 Mag.) and was surprised how heavy and “sluggish” the D/A trigger is, given that AFAIK they are basically the same revolver, the Model 19 just having a slightly longer cylinder. Both are, as far as I can see, stock, with no aftermarket parts. They even sound different when dry-fired; the Model 14 has a bright “click” whereas the Model 19 is a duller “thunk.” The Model 14 also feels smoother througout the D/A pull, whereas the I'm aware of a little "more stuff going on" on the Model 19

Thinking the Model 19 might need some attention internally, I completely stripped it down, disassembling everything except the cylinder release. Internally it looked pretty good, the only real surprise being a small section (1/4”) of roughness on the bottom of the rebound slide. This couldn’t be polished out, but I reduced it as much as was practical with 320 grit w&d, followed by 400, 600 & 1200, along with the parts of the frame it slides against. I used 600 or 1200 on all other friction parts of the action as required, with some surfaces of the trigger, hammer and cylinder stop being finished with a Spyderco ultra-fine ceramic stone. (The critical contact areas of the sear & trigger. were left alone, though.) Basically all the sliding surfaces of the action were polished to a mirror finish. The cylinder was also stripped to its component parts, cleaned and polished. I did notice some wear lines (rings) on the cylinder tube and extractor rod collar which was I was able to smooth out. I even polished the spring tube of the rebound block, and the slot in the recoil plate where the hand/pawi showed signs of rubbing against the frame. All parts were degreased and then treated with Sentry Solutions Smooth-Kote and BP 2000 (same as Brownells Action Magic II) In short, it got a complete cleaning, polishing and lubrication. I went very slowly and carefully - it took about 4 hours!

Yet the trigger feels about the same :(

Now I can put in Wolff or Wilson aftermarket springs, which will no doubt improve things, but I’m curious to know from those who have them, whether this heavy trigger pull is typical of S&W’s .357 duty revolvers of the era. The Model 14 was intended as a target revolver, so it’s possible that it received some special attention at the factory before it was shipped. But the Model 19 is also a “3T”, with the matte rib, checkered hammer, target grips and grooved trigger. Some of this may be due to the Model 19 having a heavier cylinder, which would increase the inertia during the cocking cycle, but I’m still a bit surprised.
 
The trigger systems are exactly the same. I did however shudder at your description of using sandpaper on the internals, I would not use anything but fine ceramic stones. That being said two things further will get significant improvement. Replace the trigger rebound spring with a twelve or thirteen pound version, and the leaf spring with a power rib version. The other thing necessary to get a decent DA pull is to polish the hammer fly - the moving blade on the hammer front. It needs to be super smooth on the contact surface as does the top of the trigger. The fly should not have any angles changed unless you very carefully follow Khunhausen, but the fly needs to move freely. Make sure the strain screw has not been shortened, or is backed off. This is often done by those who don't understand the mechanism, and will slow the hammer fall resulting in a "thunk".

cheers Dr Jim
 
...I did however shudder at your description of using sandpaper on the internals, I would not use anything but fine ceramic stones...

LOL! I used automotive w&d paper lubricated with oil to polish the rebound block, with the paper laid on a solid, flat surface, rubbing the block to and fro. I have 1500 & 2000 w&d as well but that's where the ceramic stone takes over. To polish the bits of the frame where it contacts, I put the paper on the end of a carpenter's pencil. The Spyderco ceramic stone was far too fine to use on these surfaces, except on the bottom of the frame where the rebound block rubs, which was now pretty much mirror bright. I used the stone alone on the sliding surfaces of the trigger and hammer. I will be ordering a fine India stone shortly, though.

... The other thing necessary to get a decent DA pull is to polish the hammer fly - the moving blade on the hammer front...

That's the double-action sear and it was actually quite rough so it got the w&d treatment, followed by the ceramic stone. The top of the trigger was also polished with the ceramic stone. The only rubbing surface I couldn't practically polish was the inside of the "hook" of the cylinder stop, but I did polish the tip of the trigger which contacts it.

The strain screw is all the way in. I know some competition shooters back this off a bit, then install a second screw in the bottom of the frame to make sure it doesn't move, but that's specialist stuff for the "Federal primers only" crowd.

As I was thinking on this more last night I'm suspecting there may be some unnecessary friction/drag in the cylinder assembly, even though I polished the surfaces a bit. Later today I'll remove the cylinder and check the D/A pull without it, and try to get a pic of the extractor rod collar etc.

No doubt aftermaket springs will improve things but I want to make sure the revolver is as good as can be before I put those in.

:) Stuart
 
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I'm no gunsmith by any stretch of the imagination, and I've never torn down any of my revolvers so take this with a grain of sand. From 17s to 629s, mine are smooth and crisp mechanisms but using someone's Chief's special, it was not so smooth. I don't think it had been cleaned since it was new in the 1970s, and while the trigger was crisp, the DA pull was laborious and required a bit of lubrication: It was in the rotation of the cylinder where the friction was the culprit.
 
I had another look at it a while ago. The only thing that looks amiss is that the hammer has a tendency to want to drift a bit to the right, noticeable when dry-firing it with the side plate off. I noticed a wear mark on the right side of the lower part of the hammer as well as a bright spot on the frame where the top of the hammer enters it. However, there is only the very faintest corresponding mark on the very edge of the top of the side plate and it doesn't seem to have any effect on the actual trigger pull. It does not actually hit the frame in normal use, though. The free rotation of the cylinder seems OK and comparable to that of the Model 14, and there is no looseness or slop.

View attachment 62567 View attachment 62568

Oddly enough, the DA pull seemed a wee bit smoother this morning, although still not as good as the Model 14. Unfortunately I don't have a trigger pull gauge so I can't give actual measurements. (A trip to the new Cabela's out here next week may rectify that.) A S&W specialist like Murray Charlton could probably figure this out but for now I'm going to try an aftermarket spring kit and see what diffrence that makes. Aside from the hammer drift thing, I can't identify anything other than a heavy mainspring as the culprit.
 
I have heard that it's not a good idea to dry fire without the side plate installed as the hammer and trigger pin are then only supported on one side. Does the hammer drift to the right when the side plate is installed?

You've done a lot of polishing which should give you a nice smooth trigger action. To lighten the actual trigger pull, the next step would be lighter rebound and main springs. I've installed Wolf performance springs in most of my S&W revolvers and they make a big difference.
 
I have heard that it's not a good idea to dry fire without the side plate installed as the hammer and trigger pin are then only supported on one side. Does the hammer drift to the right when the side plate is installed?

You've done a lot of polishing which should give you a nice smooth trigger action. To lighten the actual trigger pull, the next step would be lighter rebound and main springs. I've installed Wolf performance springs in most of my S&W revolvers and they make a big difference.

I'm not surprised that dry-firing w/o the side plate is not a good idea, for that very reason. I only noticed it when I was checking the action once I had removed the side plate. As I mentioned, there is a wear mark on the right side of the hammer above the pin, where the hammer meets the top of the side plate, but only the very thinnest of a corresponding mark on the side plate itself.- barely even a hairline. You can see the slight offset of the hammer in the pic I posted above. Just now I covered the wear spot with a black marker, reassembled the gun and dry-fired 18 times, but there was no real indication that the hammer is rubbing against the side plate now, possibly because during the detail strip I had run the ceramic file flat against the back of the side platel; if there was a micro-ridge there, that would have removed it.

So I guess new springs will be the next step. I put them in my 625 (regular model, not JM) and they did make a difference.
 
It will vary from revolver to revolver. Mass production variance , a drop in finishing QC in the 70's. A number of reasons. If you feel your hammer is dragging on one side you can recut the boss and use side shims to center it. I highly recommend Kuhnhausen's books on this if you don't already have them. For the poster that spoke of the rough action in a Chiefs special, different action. J frame coil spring vs K frame leaf spring. I have two 19's, one of which is extremely smooth, the other not so much. - dan
 
dan belisle;12900214... I have two 19's said:
Thanks for this. Good to know. Mine is a 19-4 which would place it between '77 & '84 I think. Does have the pinned barrel and recessed cylinders, though.

I don't think the hammer is actually contacting the side plate now so I'm not going to worry about that. Plus "correcting" that might also affect the even mating of the hammer with the trigger and as I recall that seems to be OK.

I'll check out the Kuhnhausen; I'd always thought of him as the 1911 guy. :)
 
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