Mystery Light Primer Strikes

[Wyo]

I have a Model 14-1 that is giving me light strikes about 1/3 of the time in double action. Single action is fine. This happens with factory ammo and handloads and with several primer brands. I have replaced the mainspring with a new, full power Wolff replacement. I’ve also installed a new, full length strain screw. The gun has virtually no endshake and is clean and lubricated. Headspace appears proper. I’m running out of ideas here. Any thoughts on other possibilities?

[.38SuperMan]

Try putting a little shim between the strain screw and the spring. I had the same thing happen to my M17. I replaced all the springs with new Wolff standard weight springs and just didn’t want to go to a heavier mainspring. It just needed a little boost and a thin shim provided it.

What I did was clean the anvil and spent powder out of an old primer cup and flattened the dimple from the firing pin. I slipped that over the end of the strain screw and that was all that was needed.

[chief38]

Let's for the moment assume your end-shake tolerance is correct and your cylinder is indexing correctly, you said you checked that out. Because you said you have changed the main spring and main spring strain screw I can only think the following:

Without having said gun in my hands, I would say you have an issue with the hammer not traveling far enough rearwards before being released in DA mode. This in turn is lowering the energy and won't have enough to reliably ignite a primer all the time.

In single action the hammer is released from a farther back position and therefore has more energy to set the primers off.

Again, without the revolver in front of me I can only guess but it sounds like that could be your issue. I'd start by checking that out. I'd also make sure your firing pin is the correct length and that it is protruding the correct amount. Has it been replaced? Is the firing pin bushing loose?

[Wyo]

Originally Posted by chief38

Let's for the moment assume your end-shake tolerance is correct and your cylinder is indexing correctly, you said you checked that out. Because you said you have changed the main spring and main spring strain screw I can only think the following:

Without having said gun in my hands, I would say you have an issue with the hammer not traveling far enough rearwards before being released in DA mode. This in turn is lowering the energy and won't have enough to reliably ignite a primer all the time.

Again, without the revolver in front of me I can only guess but it sounds like that could be your issue. I'd start by checking that out. I'd also make sure your firing pin is the correct length and that it is protruding the correct amount. Has it been replaced? Is the firing pin bushing loose?

I agree, the hammer fall lacks sufficient energy to reliably ignite the primer. I considered the possibility that the sear spring might be weakened or broken and that this may allow the hammer to trip off the double action sear prematurely, but the sear and sear spring seem fine. However, I might have come up with another possibility. I’ll test fire tomorrow if it isn’t raining as predicted. Will let you know if that works out. And, yes, the firing pin is original and intact, and the firing pin bushing is tight.

[Alk8944]

Why did you install the Wolfe spring? Were you having ignition problems before the spring change? Why did you choose a Wolfe spring instead of the S&W factory part?

If you have the Wolfe "Power Rib" spring the strain screw will seat into the groove of the power rib! This spring requires a longer strain screw than the factory spring does, Wolfe doesn't tell purchasers this! The strain screw is 8x32 NF and can be replaced with an Allen head cap screw and can be adjusted to give adequate spring tension.

If you were not having problems with the factory spring then re-install it or a new factory spring. Buy a new factory strain screw with the factory spring and see if that corrects the problem! Wolfe springs are not better than factory, only different!!!! They can cause their own problems as noted above!

[Marksman]

I've installed the Wolfe Power Rib spring in several of my S & W revolvers and never had problems of any kind.

[Bruce51]

Originally Posted by Marksman

I've installed the Wolfe Power Rib spring in several of my S & W revolvers and never had problems of any kind.

I installed one on my 686. After several light primer strikes I put back the old spring. No more misfires.

The Wolf spring is a far cry from a full power replacement. I purchased several but now I won't install them in any revolver.

Bruce

[chief38]

FYI: In "general" Wolff makes a descent quality product. That said, I have had a few of them that were NOT up to spec! If you haven't already, put back the Factory parts and retest. Wolff is NOT what they used to be with QC!

[Protocall_Design]

Just trading parts without measuring anything is stumbling around in the dark. Get a trigger pull gage, even a cheap spring one is fine, hook it on the hammer and see what the hammer pull weight is. Take the reading just as the hook on the scale lifts off the frame. That tells you how much tension the mainspring is putting on the hammer. Then you can record that number in ounces. You have to pull the trigger and hold it back so the hammer is free to move while doing the measurement. Once you find the hammer pull that gives reliable ignition with your primers, record that number and you can always dial it right back in if you ever change springs or work on the gun. You can also make a quick check to see if anything has changed. All this takes way less time to do than to read about.

You can use a headless setscrew to adjust the mainspring tension. The size is #8-32 x 3/8" long for RB or 1/2" long for SB. You have to put purple #222 or blue #242 loctite on the screw to hold it in place. Otherwise, it will gradually back out as the mainspring flexes and you will lose your setting. Don't put "just a drop" like a lot of people say. Clean and coat the inside and outside threads, screw the setscrew in, and wipe off the excess. Q tips work well for the cleanup. The setscrew will then stay where you put it, but still be easily adjustable at any time with the 5/64" or 2mm hex key.

I have been doing this on my competition guns for many years and it works great. For convenience on the range, there is a small access hole in the grip to get to the strain screw without taking the grips off.

[Wyo]

I was having problems with the factory parts so I replaced them with new factory parts. Problem continued. So I got some new Wolff parts and installed the new spring and screw. Problem continued. The Wolff spring is a full power spring, not one of their reduced power pieces, and the strain screw is full length, same as a factory screw. This is not a problem with the spring or strain screw. The gun worked fine until recently and, in keeping with the KISS principles of repair, I may have another idea. Will advise when I get a chance to try it out.

[armorer951]

Lots of possibilities here.....I would start with a complete and thorough cleaning, including disassembly/cleaning of the cylinder assembly. If the gun is not clean, examination and further measuring and evaluation of specs will be pointless.

Embedded shooting debris in and on these parts (particularly the cyl assem) can cause intermittent malfunctions and reliability issues. Give particular attention to the extractor, under the extractor, and the area under the cartridge head. Use a magnifier.

After cleaning and a wipe down, measure the headspace, or "rear gauge" to make sure it is correct. Non-magnum rear gauge should fall between .060" - .068". Smaller is better. Feeler gauge should be placed between the breechface and the rear of the cylinder in the area of the hammer nose bushing. Remember also that endshake can occur on the yoke also, so be sure to check the yoke to make sure it's properly fit to the yoke screw, and it's not moving forward when in the closed position.

Also, check the condition of the hammer nose, and spring, if the hammer nose is fitted with a spring. The nose should move freely. Check the condition of the hammer nose bushing. It may be damaged.

Another possibility is a protruding pin or pins in the hammer or trigger. The drag can sometimes cause reliability problems. If this problem exists, there will be drag marks on the sideplate and/or the frame under the parts. Offending pins can be dressed down or driven back down flush with the part.

Trigger "staging" can also cause problems if you are doing this while firing in DA.


Carter

[Dvus]

+1 for the complete and thorough cleaning of ALL components.

[WR Moore]

Read through most posts above and had a similar issue when I started rebuilding a K frame several years ago. Building from advice above:

Have you checked the yoke for endplay? You see this rarely, but it can happen. There are source for yoke shims, Power Custom off the top of my head.

You mention that this only happens in DA fire. I've found that operator error makes a substantial contribution to misfires in DA. When you pull the trigger, the top of the single action sear on the trigger engages the (primary) double action sear on the front face of the hammer and starts to lift the hammer. At some point near the end of the trigger stroke, the contact changes from the primary sear to secondary contact points. These points are the bottom surface of the "foot" where the single action notch is on the hammer and the ledge under the single action sear on the trigger.

Now, in your effort to do a slow trigger press, you may not pin the trigger all they way back and hold it there while the hammer falls. If you don't, and your trigger finger relaxes slightly from the trigger break point, the trigger is going to move forward slightly. This will cause the hammer to catch on the secondary contact points and rob the hammer of energy, causing a misfire.

Assuming you do the checks and cleaning suggested above and still have misfires, I'll bet if you indulge in trigger yanking, you won't have any problems. All you have to do is school your trigger digit to complete the trigger press.

[steelslaver]

I think mechanically the possibilities of it being the gun have been covered

But, if this only began recently is it possible that it is the primers and not the gun? Have you tried a completely different batch of ammo?

[oddshooter]

Following up on steelslayer,

I changed from CCI primers which are little harder surface to Federal which has a softer surface and is easier to get a bigger, deeper crater.

The problem of light strikes went away.

That's if you can find Federal primers.


Prescut

[Wyo]

Originally Posted by steelslaver

I think mechanically the possibilities of it being the gun have been covered

But, if this only began recently is it possible that it is the primers and not the gun? Have you tried a completely different batch of ammo?

That's my next step. I did, though, try the same ammo I was using in the 14-1 in a 15-3 at the same time and had no problems with misfires or light strikes in the 15-3. Also, when I get a light strike in the 14-1 it's easy to see on the primer. The primer just isn't getting a full hit. One other thing mentioned above - I've been shooting DA revolvers for more than 50 years and I always pull straight through. I've never liked staging the trigger and never had good results with it. So, an interesting thought, but there's no hesitation once I start the trigger pull. I've cleaned the gun thoroughly and will try to shoot it this afternoon. Hope for better results.

[RMFnLA]

Any chance some Bubba shortened the DA sear while doing a “trigger job”..?

[steelslaver]

Hmm, something restricting or cushioning the firing pin in the frame cut

[Wyo]

Originally Posted by steelslaver

Hmm, something restricting or cushioning the firing pin in the frame cut

I believe you've hit the nail on the head. I got to the range this afternoon and, after two light strikes, I poked around in the firing pin channel with a small pipe cleaner and a little Hoppes. Didn't see anything fall out but I fired 100 trouble free rounds thereafter. I'm not positive, but I think some sort of small obstruction got itself wedged into the firing pin channel - maybe a little piece of primer or such like - such that you couldn't really see it but it was enough to obstruct the double action hammer fall, sometimes enough to create the light strike. I should have thought of this earlier as I once had a Colt Detective Special with a burr in the firing pin channel as it came from the factory. That gun wouldn't fire at all until I twisted a small drill bit through the hole by hand and cleaned out the burr. Anyway, it seems the problem is solved now and, as is often the case, it turned out to be a simple one - just hard to pinpoint. Thanks for all your good suggestions.

[steelslaver]

Several dental picks with various shaped ens are good to have.

[Greyman50]

Cheap wal mart brake cleaner is your FRIEND. Remove grips/ stocks/ scales , go outside and spray. When someone brings me a Smith I always remove side plate and spray the action until its clean. Lube and reassemble, always works unless some bubba did his work inside.

[Petrov]

is 14-1 hammer different from a modern N frame?
You folks mention the DA sear? In my hammer you have a little moving "sear"? I think that I push on as I start pulling the trigger but in the end there is a part of the hammer and a part of the trigger that get engaged that is not that DA sear or what I am assuming DA sear is?

[shawn mccarver]

Originally Posted by Petrov

is 14-1 hammer different from a modern N frame?

Yes. The Model 14 is a K Frame, not an N Frame. They are not interchangeable.

[steelslaver]

You got it right the DA sear if the little spring loaded toggle like piece on the front of the trigger. It have changed some over the years, but the function remains the same. As the lower "foot" of it is pressed by the trigger it starts the hammer back, but then the end of it slips off and the hammer itself engages the trigger to complete cocking and releasing the hammer.

Watch this video and at about 20 to 22 seconds you can see the hand off from DA sear to the hammer itself being engaged then released by the trigger and again on the second slow trigger pull.

YouTube

[Petrov]

Originally Posted by steelslaver

You got it right the DA sear if the little spring loaded toggle like piece on the front of the trigger. It have changed some over the years, but the function remains the same. As the lower "foot" of it is pressed by the trigger it starts the hammer back, but then the end of it slips off and the hammer itself engages the trigger to complete cocking and releasing the hammer.

Watch this video and at about 20 to 22 seconds you can see when this occurs

S&W Trigger Action: Double Action Only - YouTube

Yes thats the one thank you folks.
So if that sear is too short it makes the hammer slip off completley and fall too soon?

[steelslaver]

If the DA sear is to long or short the hammer and trigger usually bind up. Maybe if the DA sear was really short