638-3 Failure to Fire after many years

[BanditsRoost]

I'm stumped and looking for suggestions.
I've had my 638 J-Frame for many years with no problems. Now all of a sudden I'm getting light primer strikes.

I change the hammer spring several time using Wolff, MCARBO, Wilson and factory. I've tried a new factory, the #8, #8.5 and #9 from several different manufactures. I've installed the longer firing pin. Yet I still get regular light primer strikes. It's obvious the strikes are light. Two may fire fine with good hits then the next two hardly dent the primer.
(CCI 500) I'm no gunsmith but I can take the 638 to bare frame with no problems so replacing parts would be a breeze. Is there something else that could cause the LPS's?? I've even tried the hammer spring from my .22 J-Frame. Both old and new firing pins seem to move freely and are completely exposed with the hammer down and trigger pulled.

So now I'm asking the experts, any suggestions?

[rockquarry]

I'm far from an expert, but I've had very good results, including reliability, with most guns (including a 638) by leaving them as they come from the box. I'd send the gun to S&W and have them go over it and put it back as it came from the factory.

[BanditsRoost]

Originally Posted by rockquarry

I'm far from an expert, but I've had very good results, including reliability, with most guns (including a 638) by leaving them as they come from the box. I'd send the gun to S&W and have them go over it and put it back as it came from the factory.

Thanks rockquarry,
S&W makes it plain. Since it has a Cerakote they have no suggestions or guarantees of repair. I've had excellent results on other J-Frames as well. That's mainly why I'm "stumped".
It has functioned properly for several years with the Cerakote. This 638 has less than 5k rounds on it since 1991. As mentioned, with all factory parts it has regular light primer strikes. I don't alter triggers on self defense firearms.

[kaaskop49]

Is a total of "less than 5K rounds" pushing it? That averages to less than 5 boxes a year over 20 years, but we're talking about an aluminum frame. Any chance the frame has stretched, thereby increasing the headspace? Not assigning blame here!

Kaaskop49
Shield #5103

[JimCunn]

Look for binding of yout hammer and mainspring. This doesn't sound like a firing pin problem.

[chief38]

The first thing I'd check is end-shake. This is when the parts are worn and the cylinder moves forward excessively - causing the firing pin to barley hit the Primers when the hammer falls.

If this is the cause it can be fixed with shims or stretching the Yoke.

[BanditsRoost]

Originally Posted by chief38

The first thing I'd check is end-shake. This is when the parts are worn and the cylinder moves forward excessively - causing the firing pin to barley hit the Primers when the hammer falls.

If this is the cause it can be fixed with shims or stretching the Yoke.

Chief,
I've checked the "end-shake". (thanks for the correct term) It doesn't seem excessive to me. Barely even noticeable. I'll see if I can mic it. Is there a min/max I should look for?

[BanditsRoost]

Originally Posted by kaaskop49

Is a total of "less than 5K rounds" pushing it? That averages to less than 5 boxes a year over 20 years, but we're talking about an aluminum frame. Any chance the frame has stretched, thereby increasing the headspace? Not assigning blame here!

Kaaskop49
Shield #5103

I didn't think so, but again, I'm a shooter not a, smith. I'm certain I have more than that through a 642 and a Model 36. Though the 36 is steel. Is there a min/max dimension between the hammer nose bushing and the face of the cylinder?

[3rdgeargrndrr]

Hammer having signs of drag? Is it aligned straight without play?
the hammer spring strut in the correct slot on reassembly?
Lubed properly?

[3rdgeargrndrr]

Forgot to ask, is it only happening on a particular chamber(s)?

[L-2]

...and also look at one's ammo (reloading specs; components; settings).

[JDinAZ]

May have a dirty firing pin channel. Been known to cause intermittent light strikes in the 22s. Maybe a good qtip with solvent scrub in the hole and 100psi of air is worth a shot in your 38.

[chief38]

Originally Posted by BanditsRoost

Chief,
I've checked the "end-shake". (thanks for the correct term) It doesn't seem excessive to me. Barely even noticeable. I'll see if I can mic it. Is there a min/max I should look for?

Use a Feeler Gauge to measure the barrel / cylinder gap both with & without pressure pushing rearward. See what the difference is. If it is a couple of thousandths you are ok. Some "slop" is necessary. If you have many thousandths (more than 3,4 or 5) I'd say that is excessive. Shims can be used inside the cylinder to reduce the difference, however doing that will also increase barrel / cylinder gap. Still, it is imperative end-shake is kept to a minimum. There is another method also that stretches the Yoke. Brownell's sells a tool to do that. It's sort of like a tubing cutter that scores the Yoke and stretches it a slight amount. Personally, I like the shims better.

[BanditsRoost]

Originally Posted by 3rdgeargrndrr

Hammer having signs of drag? Is it aligned straight without play?
the hammer spring strut in the correct slot on reassembly?
Lubed properly?

Yes to all of those and not limited to a particular cylinder.


I may have found a clue though. I'll report back after the range today.......Don't think I've found the problem but maybe a temporary fix. Off to the range now.

[BanditsRoost]

Originally Posted by chief38

Use a Feeler Gauge to measure the barrel / cylinder gap both with & without pressure pushing rearward. See what the difference is. If it is a couple of thousandths you are ok. Some "slop" is necessary. If you have many thousandths (more than 3,4 or 5) I'd say that is excessive. Shims can be used inside the cylinder to reduce the difference, however doing that will also increase barrel / cylinder gap. Still, it is imperative end-shake is kept to a minimum. There is another method also that stretches the Yoke. Brownell's sells a tool to do that. It's sort of like a tubing cutter that scores the Yoke and stretches it a slight amount. Personally, I like the shims better.

@Chief38,
The gap measures a snug .006" without pressure. With pressure it's not even .001" difference. IOW, .007 will not fit with no pressure. Earlier this morning with factory parts back installed it fired 20 rounds of Remington GW box with no issues....I'm loading 20 with Federal and 20 with Winchester and heading for the range. Doesn't make sense because I've been using CCI 500 for years with no problems.

[Bill In Texas]

Following, I have the same problem with a 637-2.

[jeffrefrig]

I believe it's about this time I start swearing at it! If and when you find the solution, could you please let me (us) know what you came up with for the repair, please? Good luck & God bless.

[BanditsRoost]

Originally Posted by BanditsRoost

@Chief38,
The gap measures a snug .006" without pressure. With pressure it's not even .001" difference. IOW, .007 will not fit with no pressure. Earlier this morning with factory parts back installed it fired 20 rounds of Remington GW box with no issues....I'm loading 20 with Federal and 20 with Winchester and heading for the range. Doesn't make sense because I've been using CCI 500 for years with no problems.

Using DA all 20 of the Federal and Winchester fired no problem. The 10 Factory Remington and Blazer Brass fired fine. Four of the ten loaded with the CCI 500 failed to fire. Of those four, two fired on second strike using single action. SO, does anybody know the wall/cup thickness on CCI 500 Small Pistol primers? I'm showing .019" for the CCI and .015"-.018" on the others. Could one or two thousandths really make a difference?

I really appreciate all the help and suggestions. If nothing else I've learned some things. Nice Forum.

[BanditsRoost]

Originally Posted by jeffrefrig

I believe it's about this time I start swearing at it! If and when you find the solution, could you please let me (us) know what you came up with for the repair, please? Good luck & God bless.

As many times as I've changed out rebound and main spring combinations now, I've had a few choice words flung about.

[BanditsRoost]

Originally Posted by L-2

...and also look at one's ammo (reloading specs; components; settings).

@L-2,
You may have won the cigar.....see my last post.

[3rdgeargrndrr]

Many competition guys shoot federal primers as they are pretty soft. match if they can find them.
Possibly primers left out in the elements too long? I have had a box of Winchesters that went bad ie hard to ignite, most would ignite on second or third attempt.
Originally i also thought it might have been an ammo/ primer concern. But in a self defense gun, personally I want it to ignite everything and anything put in it. Ymmv. Best wishes

[steelslaver]

I would try those primers in another jun and see what happens.

[mikerjf]

CCI’s are reputed to be harder to set off. I had one take 3-4 strikes in a 60-7 without firing... first pull in a 637 and it worked. Replaced the hammer spring in the 60-7 and a whole box worked fine.

You can’t always tell much by the dent in the primer. A lot of the dent comes from the case being pushed back against the pin by recoil forces, which of course doesn’t happen on a misfire... so even if the strike looks light it may not have been.

If it were me I’d keep at it until it is reliable with CCI’s. (Easy for me to say!

[WR Moore]

Originally Posted by BanditsRoost

Four of the ten loaded with the CCI 500 failed to fire. Of those four, two fired on second strike using single action. SO, does anybody know the wall/cup thickness on CCI 500 Small Pistol primers? I'm showing .019" for the CCI and .015"-.018" on the others. Could one or two thousandths really make a difference?

There's a thread on here somewhere where someone checked primer material thickness specs for all the manufacturers. Only one difference between brands on their claimed thickness and that had to do with the thickness on one particular type of primer by one maker.

Now then, what is unknown is their ductility (how easy it is to deform the metal) specs for any of them. This can be the "harder" issue rather than thickness of the material.

Also, there's the issue of the book specifications and what thickness of the proper materials may be available when someone has to order metal sheet for primers. Are you going to shut down or use something that's almost right?

Finally, having gone through the same issues myself (with CCI SPs), the most frequent cause is that we simply don't get the primer down solid against the bottom of the primer pocket. I vaguely recall one poster noted that CCIs diameter seemed to be smidgen larger than the others which could be an issue. [If you're going to mic primers, mic new primers, not used.]

The primer pockets themselves might be an issue, especially in used brass/odd brands. There are a couple of brass brands that seem to have "skinny jeans" primer pockets. If the edges of the pocket aren't beveled, you might chamfer them, and/or consider uniforming your primer pockets.

[rockquarry]

With some hand priming tools, it's difficult to fully seat primers with 100% consistency. When the tools become worn, the situation worsens. I bought two RCBS Universal models several years ago; neither would fully seat primers all the time and the effort to seat was considerably more (comparatively) than should have been necessary. I returned them, but perhaps I just got a couple of bad ones.

The old original round tray Lee Auto Primes would eventually wear to the point primers would often not fully seat. I had several of these. Best to throw them away when they wear out.

CCI primers may be harder than others and maybe the cups are thicker; I don't know. However, barring isolated exceptions, the differences in comparison with other primers should not be enough to prevent the CCIs from working as designed in any good quality gun in good condition that remains unmolested. If the gun has been tampered with, who knows?

No one would buy CCI primers if they were truly unreliable and their primer business would have gone under years ago. I've used most primers over the years, but far more CCI than anything else. If you have a problem with proper primer ignition, the fault could certainly be with the primer, but I'd first look elsewhere for the cause.

[BanditsRoost]

Well,
It looks like it was either bad primers or mislabeled primers.
Opened a different case (1k) of CCI 500's and all seems well.

No more Failures. Loaded 10 more from the first "suspect" case and failure after failure again. The ones that fail in the 638, 642 and 442 will ignite in my Ruger SP101 and S&W 686.


My best guess is maybe Small Rifle or Small Pistol Magnums have been mislabeled.



In any case, I appreciate all the info and suggestions. I'll label these "suspect" and use them in the Henry or one of the two magnums.

I'm just glad to have my 638 back on board the boat and back to normal.