Just got the pistol to replace the brick called Glock 21 I've used for on/off-duty use. Love the M&P, except 50% of the time, the slide does not lock back after the last round is fired. Obviously, this is not acceptable. The pistol came with two magazines, and I bought three additional factory 10-round mags. It happens with all of them half the time. is this a spring issue?

Thanks. i e-mailed three separate people at S&W and so far, no response. Not good.

Hi
Great Gun that is my issue as well. Are you a right handed shooter? Is it possible that either thumb is touching the slide lock WHILE shooting. As you are probably aware any pressure on that lock will prevent the slide from staying open after the last shot. Try shooting a few mags with your left hand and see if the problem continues

I had the same issue with mine. Long story short. I told S&W I thought it was a mag spring issue. Had to send the gun and all the mags in for them to evaluate. When it came back, all the mags had different colored springs. Problem solved.
Original springs had orange paint on them. Replacements had black.
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M&P.45 slide lock with original springs.




This is how my .357 M&P looked in slide lock and how the .45 locks now.
As you can see, the slide locking back on last round on the .45 was more apt to not happen then happen with the slide lock barely catching the slide.


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If your mag springs have black paint then the problem might lie elsewhere.
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Dance like no one is watching.

I had the same issue with one of my M&P45 mags. The spring had collapsed where the spring pitch changes. My mag springs had black paint on the upper coils. The latest color is blue. I bought new mag springs from Speed Shooter Specialties. So far so good..

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Cliff
CCSO, FPD ret, USN ret.

Yep, ongoing prob w/ the FS .45. S&W has gone thru at least 5 mag spring revisions on FS .45 mags. Newest color is indeed a light blue. Call S&W, they should send you new springs. As to how long it will take them to get them to you; good luck. Took me at least 2 months to get mine. Product manufacturing backlog(MEC-GAR! They are just slammed busy due to the fact they produce mags for several weapons manufacturers. And with "Barry" talking gun control, everybody got caught short, and have played heck trying to catch up orders.
But call Smith and ask for help. If you get a cranky customer sevice rep, hang up and try again. Some of the phone people can get testy.
Smith will make it right, period.
Merry Christmas, All.
Ofc.JL

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LEO, Instr, Armorer, Gov's 20

Well, so far I've e-mailed four different people at S&W (Law Enforcement Contacts) and it's been over 30 days and no answer. This kind of lousy customer service irritates me, since the pistol is used for work.

I struggle with this a bit with my M&P .22. Have to be careful not to ride the slide-stop.

maybe your department armorer would have some pull with S&W. Worth a shot, anyway.

DUMP using the e-mail,it will take forever to get an answer. CALL them (early morning is best) and you will get faster results.

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THIS WE'LL DEFEND ΜΟΛΩΝ ΛΑΒΕ

Check your spam folder. That's where I found my reply. Took 'em 3 business days to reply.