I have shot about 400 rounds through my 9mm Shield. When the magazine is empty, the slide rarely locks back. Ammo is usually Winchester FMJ 115gr but have used various kinds. I estimate that the slide locks back maybe 10% of the time. I haven't worried too much about it because I don't carry any extra ammo for edc but I know it should lock back.

I wondered if the recoil spring is too strong and preventing the slide from going far enough back. It does eject normally. If I rack the slide back by hand with an empty magazine, it does lock back.

Any suggestions?

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does it do the same with other magazines? Ron

Yes, both magazines rarely lock the slide back.

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How does the slide stop look.. wear patterns and such. I would give S&W a call about that.. Be prepared to send the pistol back to the mothership for a week or two.. Ron

Check to make sure your thumb is not riding the slide stop. Most times this is the problem.

That and a good cleaning might help.

I agree with patbelly..............my son had issues with this when shooting my shield I on the other hand have never had it happen to me. He adjusted his thumbs and the problem went away.

I just had this problem with my FS 9mm. It was my thumb resting on the slide release. Adjusted my grip slightly and all has been well.

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M&P FS 9mm
M&P Shield 9mm

+1 for the thumb on the slide stop, it used to happen to me on a 22 pistol I use for cheap range practice. I made an ajustment with my thumbs now it locks back every time.

Definitely check your thumb position as the others have said. This problem occurs a lot with Sigs. Doesn't take a lot of thumb interference to mess up the operation of the slide stop.

Hmmm, call me crazy, but since no one else mentioned it, the problem COULD be your thumb position. It's a rare occurrence, that's probably why nobody else mentioned it. :-D

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M&P40c/15-22/SD9VE/Mossy500

I think it may be my thumb position, based on these replies. I'll check after this storm passes. Thanks for the replies.

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