Shield Fails To Lock Back On Empty Chamber

M

MrBot

New member
I put about 200+ rounds of various ammo through my new S&W M&P Shield 9mm & the only malfunction was its failure to lock back once & that was on the very 1st mag. I went to the range y'day & 4 out of 8 mags I got a failure to lock-back. ..just wondering if this is common with the Shield & if maybe it should be sent in to S&W? The gun is very clean & lightly lubed. And, no, I don't limp wrist it. The hg has never jammed.
 
If it only happens with SOME magazines, it's probably a mag issue, not a gun issue.

How many magazines are involved? If just two or three, it may be one problem mag issue, and you're hitting the problem with the same mag (or mags).
  • Just checking to see whether an empty mag will engage the slide stop and hold the slide open when the slide is racked would be a good first step.
If it wasn't happening with a NEW gun, I'd suspect weak mag springs -- but that usually happens later in the mag life. (If you've disassembled the mags, be sure that the spring is installed correctly and supports the front of the follower -- there's a diagram in the user's manual.)

If you're using more than two magazines, marking them on the bottom with tape will help you identify a problem mag.
 
With small guns it’s easy to bump the slide stop with your thumb during recoil.

Like Walt said put an empty magazine in the gun and pull the slide back to see if it will lock open.
 
I find brand new guns of all types suffer various weird malfunctions. Some of this has to do with various packing greases, anti-rust preventatives and excess lubricants on the weapon and some has to do with new parts that maybe were not cut 100% correct.

Even if your Shield was test fired at the factory they likely did not use the same magazine that came with the gun.

If it only happened once and on the first magazine I would not let it bother me at all. IF it continues to happen it would be worth looking in to.
 
Sounds like a mag issue. How many mags are you using? If you only have one, it's worth trying another one to rule out it being a gun issues vs a mag issue.
 
expendable: said:
With small guns it’s easy to bump the slide stop with your thumb during recoil.
Click to expand...

Big-handed folks shooting small guns often bump the slide stop with their thumb knuckle, so the slide often doesn’t lock back on an empty mag. Ask me how I know this!

When I shoot Glocks, this never happens to me, even with the subcompacts. My HK’s, and my Walther PPS-M2 can do this from time to time.
 
Do you shoot thumbs forward? It might be you and could be a slight training issue. I do this too on my Glock and Shield. I slingshot reload anyway, so it doesn't bother me that much.
 
You give it a bath before shooting it the first time? All new firearms require cleaning before shooting.
Isn't likely to be a mag issue with 4 out of 8 failing. It's not clean after 4 to 8 mags either.
"...weak mag springs..." Springs do not lose temper from being used.
 
I agree with the folks that mention the possibility you might be hitting the slide stop. You could shoot it with your left hand and see if the problem goes away.
 
T. O'Heir said:
...Springs do not lose temper from being used.
Click to expand...

As a general rule, you're right -- but springs CAN fail from being used, and with some magazine designs (mostly hi-cap mags), mag springs or even recoil springs can also fail over time by being kept fully compressed for long periods. (Most fully-loaded mags don't fully compress the mag springs, but a few do.) That's why Wolff Springs recommends, as a general rule, that you download high capacity mags a round or two if they're going to be stored loaded for long periods.

We know it's a new gun, but we don't know that all of the magazines are new. The original poster hasn't been back to offer any updates.
 
Before doing anything else, Do take a close look and be sure you aren't accidently (and unknowingly) bumping the slide release when shooting.

It happens more often than you might think, with some people and some guns.
 
I do not own a Shield any longer, nice gun, but just preferred something else. But, just like a lot of guns, I would check out the condition of the slide lock spring, or the Magazine catch spring.
I have a feeling your issue is a easy fix. Best of luck.
 
If it only happens on the last round with some magazines, it may be that some of the mags are the problem rather than the shooter's grip.

As noted earlier, numbering the mags would help the shooter to determine if only certain mags had the problem.

He can check that pretty easily by only loading 2-3 rounds per mag and firing away!
 
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Wow! ..wasn't able to do much range time since my OP in September. Heck if I know why I, or the hg, had a bad day way back when. This little hg has been thoroughly clean & lubed a lot since I 1st got it new. I put a couple of hundred rounds of various ammo (mostly hp) through it since my OP & the hg has worked flawlessly. ..appreciate all the input & will keep these notes should I run into this problem in the future. As for now I'm happy.
 
I have an old FIE Titan/Erma Excam/Targa GT380.
It has a slide lock too that I never knew about until I ran some hotter than normal handloads.
Surprised me a bit.
Normal factory loads - no.
Anything loaded a bit hotter - locks every time.

I'd be curious to see if using +p had any effect.
However since it seems to have corrected itself - I might be tempted to chalk it up to teething pains.
 
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