The last time I took my Performance Center Ported 9mm to the range the slide would close and chamber a round when I installed a new full factory magazine. The gun has about 1000 rounds through it and this has never happened before. I have shot Blazer Brass 115 fmj since i bought the gun new and this is the ammo that was in the magazine when i experienced the issue. The problem tended to occur when I slapped the magazine home rather than sliding it in gently. Has any other M&P owner experience this and if so what was the cause and what needs to be done to stop this from happening

Not to worry, just don't slam the mag into the well so hard. It can happen on many bottom feeders. My CZ 75B did it the other day when I got a bit exuberant with loading it.

It's called auto forward. My 40c does this as well and I like it. Makes for faster mag changes as long as it is consistent.

That's not unusual across the whole line of semi autos.

My 9mm Shield NTS does this sometimes too.

This depends on how hard you insert the mag, and how many bullets are in the mag. (and how hard you grip your gun). This is common, if you look at the bottom of this page you will see links to multiple threads (and there are many more) about this topic.

If you slap a magazine in with any gusto it will often release. If it always releases no matter the force used...you may need a fresh spring for that slide stop assembly.

Like Goldilocks & the bears, it needs to be juuuust right.

Thank you all for the reassurance. I just wanted to be sure that nothing bad was going on with my gun.

I have 2 FS M&P and they both do it however my Shield does not. It can depend on the number of rounds in the magazine also. If the magazine is close to empty the slide might not release.

I personally like it. Comes in real handy when shooting IDPA. On the other hand since my Shield is my carry weapon I am always concerned that in the heat of a potential situation my instincts will take over and I will forget the Shield slide does not release because I shoot the FS so often.

Yeah, S&W claims it's not a "feature", but I'm not complaining about mine doing it. My H&K USP 9mm Compact does it too. It's a good thing.

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If you ever shoot IDPA or USPSA, you'll be glad it does this. Much faster reloads.

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My FS M&P does this consistantly with a near full mag only. Great 'feature' in my mind!!! Have never had this happen with my Shields though. Good to hear it is common.

Auto-forward is not trustworthy. I have gotten failure to feed malfunctions from my pistol. Racking the slide has fixed it. (I guess this is an argument for racking instead of using the slide release.)

https://youtu.be/C-w2i7OWkyY?t=30s

This is a malfunction in your pistol.

The fact that it occurs in other pistols (when it's not a design feature) doesn't make it a good thing.

You shouldn't have to worry about inserting a magazine 'gently' so your pistol doesn't malfunction.

One should always slam the new magazine home briskly to be sure it locks in place.

The idea that this malfunction facilitates quick reloading misapprehends proper gun management: you should never shoot your pistol 'dry' so you've locked the slide back. You should drop the mag with the chamber loaded and at least one round in the mag. (The round in the mag facilitates the mag dropping free of the pistol).

S&W says it's not a malfunction. They say it can happen sometimes.

Understand, this is not a malfunction. If it didn't chamber a round or the action caused some issue where the gun wouldn't fire, then it would be a malfunction.

Now, you could call it a design flaw. Of course that depends on your point of view. If you like it, it's not a flaw. If you don't like it, it is a flaw.

The reason this happens is simple force vectors. Because there is a spring pulling down on the slide stop, any rearward movement of the slide will release the slide stop. Therefore, if the force is in any direction other than up, it can cause the slide to move a tiny bit. This movement releases the slide stop and allows the slide to go forward.

I don't see it as an issue and can find no situation where it is a problem.

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It is in no way a malfunction. It is physics. I have explained it on at least one other thread, and I decline to do so again. Go here:

Mag Loading Question

As for your assertion that you should never shoot your pistol dry, I dispute that as well. You shoot to stop the threat. If that necessitates all of your rounds in rapid succession, so be it . . .

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Wisdom comes thru fear . . .

I agree with you if one is talking about stopping threats, but I don't stop threats, I just shoot paper. If I shoot to slide lock, my stage plan is flawed (or I screwed up and missed a bunch). Reloading before slide lock is just faster. I drop mags with rounds in them on every reload (unless I screw up )

You have the opposite problem of many folks who say their slide stop/release is hard to release.

First of all, being a new gun, parts wear--recoil springs get a little looser; slide stop and the slide notch surfaces get a little smoother from wear--this condition is likely not only to continue but actually get a little easier to perform.

But all is not lost. You can adjust your slide stop to work any way you want it to by simply adjusting the friction between the lever and the slide.

http://smith-wessonforum.com/138832427-post13.html

I have thousands of incidents of auto-forwarding purposefully induced on my pistols over the past 20 years. I have never had an AF fail to pick up the top round from a mag and chamber it. The physics require the mag to be fully inserted before the slide stop will drop and release the slide.

Also, it makes no difference how many rounds are in the mag since there is nothing above the mag when it is fully inserted. The compression of the mag spring has no relation to the release of the slide stop when the slide is locked back.

I regularly do an Administrative Load this way:

With the gun pointed in a safe direction, slide locked back and only one round loaded in a mag, I slap the mag home, the slide closes and loads that top round. I remove the empty mag and insert a full one, tugging on it to ensure it is properly seated.

This accomplishes two things. It fills the gun to its maximum capacity, and if the firing pin is stuck in the forward position, it would allow only one round to fire rather than having the gun go full auto and emptying the whole mag. BTW, this has never happened to me or anyone else I know, but it has happened.

Break in your new gun and adjust its mechanics to meet your needs. It's your gun. What's right for you is what's right.

Not if the magazine floor plate catches your dangling, grip-holding pinky finger on its way into the well. Seen it happen, especially under duress, or when reloading conditions aren't ideal. Don't try to duplicate it. Hurts like the dickens, I've been told. That being said: Never depend on an event not designed into the weapon . . .

(ps: I also know people who have fueled their still running mower thousands of times without incident. I know another fella' with a new garage because he tried it.)

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Wisdom comes thru fear . . .

No. In fact, it doesn't require a magazine at all. I can get all of my M&Ps to close the slide if I just strike the bottom of the magwell.

I'll have to make a video.

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^ this ..my FS .40 does this, I wish my shield did too I like it

Correct. Mine too.

I was referring to the unlikelihood of a jam, malfunction or failure to load a round when a magazine is slapped in all the way with the slide locked back.

Improper insertion of the mag--getting something in the way of full insertion--will foul any loading procedure. So will inserting an empty mag by mistake. So will having the top round loaded backwards. So will using the wrong caliber. So will putting the mag in backward.

Do I need to go on?

This has nothing to do with whether a properly loaded and inserted mag will reliably load the top round from a seated mag upon auto-forwarding.

You must not shoot IDPA, as if you drop a loaded mag, you have to pick it back up.

Also, I always use the "auto-load" feature in matches and it has never caused a malfunction, ever, in five years of competing.

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You're correct, I don't shoot IDPA (anymore). USPSA has no such rule about dropping mags with rounds in them. I plan where to do reloads so I don't have to let the pistol go to slide lock. Typically when moving between shooting positions (another IDPA "no-no). One less thing to do on a reload. (waiting for the slide to drop, either "auto load", "sling shot" or "lock button")

But with my pistol, IDPA wouldn't even let me in the door.

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Hey, I'm outta this. You roll your way, I'll roll my way. If you think it's a proper operation, who am I to say different? Of course, as I've told many people over the course of my career, just because you CAN do something doesn't mean you SHOULD do something. Good advice for most life arenas . . .

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Wisdom comes thru fear . . .