640: light primer strikes

I went shooting today. I shot some 357 reloads in my 586 and in my 640. Everything was fine in my 586. I had about 5 out of 20 misfires with my 640. I then shot some 38 +p's in the 640, and they worked fine. All the misfires had light primer strikes. I was using CCI small pistol magnum primers for the 357s and CCI small pistol primers for the 38s. All the primers appear to be seated correctly, although I am farely new at reloading. This is my carry gun so I want it to shoot 100% of the time. I do shoot it a lot. Any suggestions? I know it could be a lot of things. I'd be interested to hear a few opinions.

Did the misfired rounds fire when you tried them a second time?
(did you try them a second time??)

If so then they were not seated properly.

Does the gun have it's factory springs or has any trigger "work" been done?

Did the suspect rounds fire in the 586 if you did not re-strike them in the 640?

Rule3 said:

Did the misfired rounds fire when you tried them a second time?
(did you try them a second time??)

If so then they were not seated properly.

Does the gun have it's factory springs or has any trigger "work" been done?

Did the suspect rounds fire in the 586 if you did not re-strike them in the 640?

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All good questions that need to be answered before we can go further. Also, have you had any problems with factory ammo in your M640?

Try Federal primers.

I shot a bunch of said rounds in my 586 without any problems. Misfired rounds make me nervous. I inspected a few briefly and threw them in the woods. I didn't try and shoot them again.

The gun: I bought it used 6 years ago cheap. It had an unusable trigger pull. I took it to my gunsmith. He said Bubba must have worked on it and replaced something backwards. It was an easy fix. Except for this, I consider it a factory trigger. I have shot this gun a lot and have not had any problem with factory rounds. It is a gem of a gun. Very accurate. I just started reloading last month.

I still have some of the rounds. The primers sure look like they are seated correctly. I'm wondering if my gun doesn't like CCI small pistol magnums or if I have a bad batch of primers. Or maybe I've stretched the frame out on my dear little j-frame. I haven't had any problem with CCI small pistol primers(not magnums).

Finn McCool said:

I shot a bunch of said rounds in my 586 without any problems. Misfired rounds make me nervous. I inspected a few briefly and threw them in the woods. I didn't try and shoot them again.

The gun: I bought it used 6 years ago cheap. It had an unusable trigger pull. I took it to my gunsmith. He said Bubba must have worked on it and replaced something backwards. It was an easy fix. Except for this, I consider it a factory trigger. I have shot this gun a lot and have not had any problem with factory rounds. It is a gem of a gun. Very accurate. I just started reloading last month.

I still have some of the rounds. The primers sure look like they are seated correctly. I'm wondering if my gun doesn't like CCI small pistol magnums or if I have a bad batch of primers. Or maybe I've stretched the frame out on my dear little j-frame. I haven't had any problem with CCI small pistol primers(not magnums).

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You are just guessing.

Live ammo should never be "thrown in the woods"

If you have some that have a light primer strike, try them again in the same gun. If they go bang, they are not seated enough.

"Occam's Razor"

Rule3 said:

You are just guessing.

Live ammo should never be "thrown in the woods"

If you have some that have a light primer strike, try them again in the same gun. If they go bang, they are not seated enough.

"Occam's Razor"

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I agree with everything he said, except primer seating. With a standard firearm in factory condition it should fire good ammunition 100% of the time.

You say you "consider" it to be a factory trigger after taking it to a "gunsmith" who made a remark that "Bubba must have worked on it and replaced something backwards!" If he doesn't KNOW then he is no Gunsmith, just a hammer mechanic! You have no idea what is going on in that gun!

Take the gun to a GUNSMITH, or send it to S&W, and have the springs replaced with factory new ones and chances are far better than average that the mis-fire problem goes away.

Consider what you, yourself, said, that the same ammunition fired in the 586, but not in the 640! It isn't an ammunition problem, it is the gun!!!!!!!!!!! The shoemaker that worked on it probably was right about "Bubba", and it was probably HIM.

WHY would you throw away what is perfectly good ammunition simply because you tried to shoot it in what is a defective revolver and it wouldn't fire, when you knew it would fire perfectly well in the other gun? This simply makes no sense.

RULE 3:

The only reason I disagree on the seating point is this is basically an old wive's tale. A gun with adequate hammer/striker energy will fire good primers 100% of the time, even if they are not seated fully. This is personal experience. In 50+ years, and something on the order of 1 million rounds loaded and fired, I have made mistakes and had primers not fully seated to the point of them dragging heavily on the breech of the revolver, probably a few hundred of them over this time. I have NEVER had a mis-fire as a result. As a matter of fact, I do not recall EVER having a mis-fire with a cartridge which I loaded, for any reason at all!

The only exception to this was way back in the days of steel dies and lubricating cases. I used Coleman Fuel (R) to de-grease the sized cases for one box of ammunition, and had nearly 100% failure to fire with that 50 rounds of ammunition. I KNOW what caused those, so I don't consider those in overall experience. [FWIW, Carbon Tetrachloride and Trichloroethane didn't give any problems (gasp!).]

That is your experience which I respect. I have had a few primers not fire the first time and gone bang the second. Mostly Wolf which tend to be harder to seat.

I have Wolf spring kits in all my revolvers.

Many variables here, the OP's 586 may well have a stronger mainspring than the 640, did he fire it single or double action(586)? What method was used to seat the primers, what brass, were the pockets clean??. He is a new reloader etc.

I am only trying to rule out the simple, easy factors first before "it's the primers fault" Only after his second post do we discover that the gun may have had things done to it, so yes it may very well be the gun.

EDIT:
Manuals by Speer, Lyman, Hornady and Lee all have notations of incorrectly seated primers causing misfires. Even seating primer too deep and crushing the internals may cause a misfire. A crooked (off center primer) and too high of a primer will cause misfires.

I went fishing today and shot off the last 15 rounds in my 640 that I had from the batch in question(not at fish). They all went off on the first try. So I have no new information.

Just to answer a few of the questions that were in the last few posts.: I shot my 586 single action. I have been seating my primers with an RCBS hand priming tool. I have had a few issues with it. Sometimes it sticks and I end up with two primers in the tube, and I also had an inverted primer eventhough they were all upright in the loading tray. The brass is mixed. I did scrape out the pockets with a small screwdriver before seating primers. I tumbled my brass with a corn cob media.

The gun: I have shot this gun a bit(estimate: 600 factory magnum rounds and 2,500 non magnum factory rounds over the last five years). Probably more. No misfires.

Thanks for the insight. I appreciate it.

Magnum primers are made out of thicker material and require more striking force to fire. You may have weak/changed springs in your gun which are working fine for standard primers, but may be too weak to fire off the magnums. In time, you will probably be getting mis-fires in your standard primers as your springs weaken over time. I would simply change out the mainspring with a factory one.

Thanks for all info. I think I'll change out the mainspring sooner rather than later as this is my carry gun I'm talking about.

I went shooting this evening. I shot 30 rounds of 357 in my 640. My hand is little sore. I had 4 rounds that did not go off(CCI magnum Primers). 2 rounds went off the second time I shot them in the 640. 1 round went off the 3rd time. One round did not go off after 5 tries. It fired in 586, but on the second attempt. I did shoot about 30, 38 +Ps, and they all worked 100%.

So I'm thinking about new springs. This is my carry gun and I really like it. Any recommendations on springs. Any other advice is appreciated.

Thanks in advance. This forums rocks.

Wolff Springs. Good people, fast delivery

Springs for SMITH & WESSON J FRAME Revolvers

You can get the standard power 8.5 lbs or extra power 9.0 lbs.
Only need the hammer (main spring)

For the price I would buy both. Try the standard first.

They are very easy to install. If you have not done one, let me know and I will walk you through.


Just a thought. This may be a long reach, but you stated you shot a bunch of 38 specials and they all worked? Did you load those?

When you chamber the 357"s do they drop right in the cylinder or do you need to push them in?. Are they easy to extract? I am thinking carbon build up from the 38's. Be sure to brush out the cylinders with a over size brush so the 357's are not "hanging up"

I loaded the 38's myself. They had CCI small pistol primers as opposed to magnums. The 357's drop right in. I don't clean my guns as often as I should, but I do give the cylinders a good scrubbing when I do. The extraction is difficult to say because it has a short extraction rod, so they don't just pop out with one push, but they don't seem to stick.

I would appreciate a tutorial on replacing the springs if its not too much trouble. And thanks once again.

Finn McCool said:

I loaded the 38's myself. They had CCI small pistol primers as opposed to magnums. The 357's drop right in. I don't clean my guns as often as I should, but I do give the cylinders a good scrubbing when I do. The extraction is difficult to say because it has a short extraction rod, so they don't just pop out with one push, but they don't seem to stick.

I would appreciate a tutorial on replacing the springs if its not too much trouble. And thanks once again.

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When you get the springs, send me a PM and I'll go over it.

Do you have good screw drivers to take the side plate off? Don't want any buggered screws. If you have not taken the side off before, no worries it's not a problem and nothing is going to go flying off into space.

These are the best drivers for the money, for general use and not breaking the bank. Made in USA and not junk like the other sets.

Model 8900 27-Piece Deluxe Screwdriver Set

I've got good screwdrivers. I'll order the springs tomorrow. Thanks

Finn McCool said:

I've got good screwdrivers. I'll order the springs tomorrow. Thanks

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Here. I found this for ya. It is removing the IL so you do not need the whole video. You do not need all the tools nor do you need to take off the cylinder latch.

Pretty much stop at 3:55 into the video.

After you pull the hammer strut and spring out, simply hold the strut and rubber washer and pull out the paper clip.

Slide the new spring on, compress it until you can put the paper clip back in. Insert the assembly back in the gun, hold the strut and pull out the paper clip.

Put side plate back on, don't bugger the screws and you are done!

S&W Internal Lock Removal - YouTube

update: I mistakenly order a reduced power hammer spring. I installed it anyway. It makes for a really nice trigger pull, but I now have about 40% misfires, even with regular primers. I've got more springs on the way. If that doesn't fix it, I recon it's gunsmith time.

What can anyone tell me about Wolf's reduced power hammer spring? Would that be responsible for a great many misfires? Thanks

Finn McCool said:

update: I mistakenly order a reduced power hammer spring. I installed it anyway. It makes for a really nice trigger pull, but I now have about 40% misfires, even with regular primers. I've got more springs on the way. If that doesn't fix it, I recon it's gunsmith time.

What can anyone tell me about Wolf's reduced power hammer spring? Would that be responsible for a great many misfires? Thanks

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In my experience, not likely to be the problem. I have them in all my revolvers and shoot Wolf Primers which are pretty hard.

It is only 1/2 lb (.5) different than a factory spring. You could have a bad firing pin, bad gap or who knows?? If you can't send it to SW then yes it seems like a good Gunsmith is needed.

Changing the rebound spring is what makes for a much better trigger pull but has nothing to due with the hammer strike.

Thanks for the feedback, Rule3. I've got the springs on order. I'm going to try the stronger springs before taking it to a gunsmith. You mentioned that I might not be able to send it to S W. Is it difficult to send a gun to SW for repairs? The gun laws in my state are fairly easy.

Thanks again.