M&P Shield 40 malfunction (failure to return to battery???)

Bamairish79 · Apr 20, 2021

Shield 40 malfunction (failure to return to battery???)

I’m not sure I can accurately call my malfunction a “failure to return to battery” but I’m not sure what else to call it. I’m new to the forum, have been an amateur shooter for years, but have never had any malfunctions serious enough to have acquired any troubleshooting experience.
I bought the m&p shield 40
secondhand a carry weapon for my wife having heard nothing but great things about it. On my first and only trip to the range with it, it failed to fire 100% of the time with the exception of the first round in the magazine. It happened with all 3 factory mags and about 20-30 rounds each of Remington FMJ 180 gr. and Federal FMJ 155 gr. The slide returns to position and the round seems be seating properly. It is (seemingly) cycling completely but I can’t seem to isolate the issue. Any help would be greatly appreciated.

grizz700 · Apr 20, 2021

So you are saying the slide is completely closing but the gun will not fire a loaded round? When the first round is fired is it ejecting the case properly? Have you removed the slide and cleaned and oiled the sear assembly? Just throwing stuff out there for a starting point.

jurek · Apr 20, 2021

Bamairish79 said:
The slide returns to position and the round seems be seating properly. It is (seemingly) cycling completely but I can’t seem to isolate the issue. Any help would be greatly appreciated.

In this case it's not "out-of-battery".
If you are sure the cartridge seats perfectly in the chamber, check the striker pin.
To eliminate "magazine issue", just load one into the chamber, remove the mag then fire. If all is good - to this again. If all is good again.... that's the moment we have to start thinking about something else than striker issue.

Bamairish79 said:
It is (seemingly) cycling completely but I can’t seem to isolate the issue.

To be sure it's fully cycling - if it's not firing, press the slide from the rear and fire again. Does it help?

Saudade · Apr 20, 2021

Check the primers on the cases. Are there any dimples? The fired ones should be fairly prominent and deep. How are the others?

swsig · Apr 20, 2021

There is some good advice above. It looks your slide is not fully closing after you fire. All it takes is to have a very small, barely noticeable gap between the breech face and the loaded round for the firing pin to miss the primer. Jurek's advice to press on the back of the slide is the first thing I'd try. If it moves forward even slightly, it is not returning to battery. If this is the case, it could be due to poor lubrication, but if you've lubed it properly, it's more likely that your recoil spring assembly is worn out. Although Shield recoil springs are quite robust, they do wear out eventually. Since you bought yours secondhand, there's no telling how many rounds it has on it. Just to be on the safe side, I'd order a new recoil spring assembly from S&W customer service. They used to give them out for free as part of their lifetime service policy, but I'm not sure if that's still true. However, even if S&W charges for them, they don't cost much and a new one is cheap insurance against future failures to fire. If proper lubrication and a new recoil spring assembly don't solve your problem, a trip back to the factory may be in order for your Shield. It's free, and S&W will even pay for shipping.

Good Luck, and Welcome to the Forum!

Bamairish79 · Apr 20, 2021

Wow! I wasn’t expecting such a strong, quick response. Much appreciated.
1) the slight is returning fully forward — or, at least, appears to be by my naked eye.
2) The spent cartridges are ejecting properly without fail.
3) I did clean and lightly oil the sear and all moving parts. I think I will oil a bit more liberally before the next range trip.
4) Jurek, I haven’t tried firing a single round from either mag. What would the purpose of this exercise be, though? The first round of each mag is the only one that IS firing, I assume because I rack it by hand. It’s possible I’m misunderstanding.
5). I also didn’t think to push the rear of the slide since it looked as if it was properly seated. I’d never heard of this sort of malfunction before encountering it either though. I’ll definitely try that and get back to you.
6). I did check for dimples on the primers of several of the of the misfired cartridges; not a scratch.
7) Swsig, I actually emailed the guy who sold it to me and he said he’s only put about 500 rounds through it and never had an issue. Of course, I encounter people on a regular basis for whom lying seems to come more naturally to them than breathing, unfortunately. I did order a 20 lb. Wolf spring assembly yesterday, however. Does Smith & Wesson’s lifetime sevice warranty transfer over to a secondary owner?

I appreciate everyone’s time spent trying to help me track down thiis issue. You are all much appreciated.

Echo40 · Apr 20, 2021

6). I did check for dimples on the primers of several of the of the misfired cartridges; not a scratch.

Well, there's your problem. By the sounds of things, either the slide isn't returning to battery so the firing pin isn't hitting the primer or the firing pin is broken. (Most likely the former since you said that the first round that you manually loaded goes off without fail.)

If you replace the Recoil Spring Assembly with a proper factory replacement, then all should be well. I would not advise that you go overboard with some excessively heavy aftermarket RSA which will only make the slide more difficult to rack, may possibly impede reliability with lighter loads, and most certainly will cause reverse battery of the slide.

Does Smith & Wesson’s lifetime sevice warranty transfer over to a secondary owner?

This is something of a gray area as officially their warranty is exclusive to the original owner, but Smith & Wesson appears to play fast and loose with their own rules, and seems more concerned with customer satisfaction, so they generally don't ask whether or not a customer is the original owner when contacted regarding service/repairs, they'll typically just swallow any minor expense of fixing small problems for the sake of keeping the customer happy.

cracker57 · Apr 20, 2021

not trying to point fingers but no one has mentioned limp wristing, does it do this when someone else shoots the pistol?

Tiribulus · Apr 20, 2021

Maybe somebody lubed the inside of the striker channel in the slide and there's gunk in there hindering the movement of the striker/firing pin.

Or maybe just over lubed the gun in general and some got in there. It should be dry n there.

jurek · Apr 21, 2021

Bamairish79 said:
5). I also didn’t think to push the rear of the slide since it looked as if it was properly seated. I’d never heard of this sort of malfunction before encountering it either though. I’ll definitely try that and get back to you.

I will start with this. Be sure slide locks the chamber properly.

Bamairish79 said:
4) Jurek, I haven’t tried firing a single round from either mag. What would the purpose of this exercise be, though? The first round of each mag is the only one that IS firing, I assume because I rack it by hand. It’s possible I’m misunderstanding.

The reason to do that is to eliminate any problem with magazine. No mag inserted - no interaction with moving parts.
If you want to find the problem, you have to isolate it from anything else what can cause the issue.

Bamairish79 · Apr 21, 2021

1) Forte Smitten Wesson, I’ll get back to you with an update once I’ve received the new spring assembly. Also, thank you for the warranty info. That’s definitely worth a try.
2)Cracker57, I’m definitely not limp wrist if. My wife was with me at the range and could have been accused of it occasionally the first few times she fired it. I think I read somewhere that that’s the most common cause of failure to return to battery, but I’m certain I wasn’t limp wristing nor was
my hand or finger coming into contact with the slide.
3)Jurek, I think I’m understanding what you mean now: chamber a round, then remove the magazine to rule out interference from the mag. Gotcha.

Thanks all. I’ll be back with updates and, hopefully, a smoothly operating Shield in a week or so.

Zed16 · Apr 21, 2021

I have a 2019 Shield 1.0 that would randomly fail to fire. Turned out to be a small piece of steel or wire - looked like it came from a wire brush - was embedded in the plastic of the striker assembly. I cleaned out the striker channel, removed the very small wire piece from striker assembly, and no more failures. I also bought a few spare striker assemblies.

M&P Shield 40 malfunction (failure to return to battery???)

Bamairish79

grizz700

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jurek

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Saudade

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swsig

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Bamairish79

Echo40

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cracker57

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Tiribulus

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jurek

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Bamairish79

Zed16

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