Sorry if this is old news to you guys. I did a short search and didn't see it so...


I just got an M&P 45. When inserting a magazine with the slide locked back, it releases the slide upon insertion. Unless I'm really gentle with the mag, the slide will drop immediately and chamber the first round.

Is this normal?

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Freedom isn't free.

I don't know about the S&W but my dads bersa does the same thing. I guess it's like tactical or something.

Yes it's normal.

My roommate's 45 will do release the slide when inserting a mag with little force. Our fullsize 9 and 9c will not unless we do a "45 degree bump'

The condition is called "auto forward". Somewhat depending upon design, it's frequently a clue that you're being entirely too manly in inserting the magazine. The slide is locked back, there's no resistance to seating the magazine, as a result, there's no need to slam the magazine in.

Current best practice is press the magazine into place, then pull on it to ensure it's latched.

And yes, the thread(s) are here. Again, and again and again........

Yep most of mine do this if you slam them too
Hard at the wrong angel

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D.

I just bought the M&P40 (sold my SD40) and had the same issue that concerned me too until I spoke to S&W techs and several gunsmiths I know as well as a police armorer.
I was told the same thing by all of them and that is that this weapon was designed for Military & Police, hence the name M&P in any caliber, as a tactical weapon and was designed to release the slide when slamming a new magazine home to eliminate the need to manually release slide in the event that a quick reload was necessary. Only the M&P series are made this way. As a former LEO I wish this feature would have been available in my day and it is certainly a welcome design as long as you become comfortable with it and shoot accordingly. If you don't like this feature than a Ruger SR9 or SR40 or S&W SD9 or SD40 (Self Defense) line might be a better choice for you.

NO IT IS NOT NORMAL.

I will have to second the NOT.

Don't be intimidated if some of the guys seem frustrated about the repeat of a common question.

While Search is certainly your friend, we are all here to learn together.

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Incoming fire has right of way

Then why on page 17 of the owner's manual does it say, "WARNING: DO NOT USE EXCESSIVE UPWARD FORCE WHEN INSERTING A LOADED MAGAZINE INTO THE PISTOL. EXCESSIVE UPWARD FORCE COULD CAUSE THE SLIDE TO MOVE FORWARD, CHAMBERING A ROUND AND MAKING THE PISTOL READY TO FIRE."

Seems like per the manual it will always do this with excessive force. It does not seem like this is a malfunction, but more of a warning (legally speaking) that this could happen.

I have heard of numerous brand polymer guns and have owned two different brand polymer guns that do this. The guns function fine. I consider it a bonus during competition, it equals faster reloads. I would not stress over it.

Now you've gone and done it, confusing the issue with facts.

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Minimize the variables

Rastoff,
just was gonna quote this also. This applies to all M&P's as the manual is the same for all but the shield. I did not read the separate shield manual.
Chuck

DUH, I just noticed this thread is over a year old, I'll bet he has the answer already. LOL

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Criminals don't register guns.

Slide closing on a hard mag insertion is very simply a friction issue. All my pistols have this "feature" because I adjust the angles and polish the mating surfaces of the slide and the stop. I also don't have to slam it hard; just very firmly--just as I would on a tactical reload with a full mag on a closed slide. Same force, all the time.

I do practice regularly with a gentle insertion and no "automatic" closing. Thumb release the stop. No big deal. My thumb is headed that direction anyway.

Not rocket science. You want it and it doesn't do it? Polish.

Does it and you don't want it to? Rough up the surfaces, or slightly change the slide stop interface angle to create more friction. Using the thumb release will take more pressure.

Change back and forth any time. The polishing/roughing is so minor that you are not really removing metal.

BTW, my new FS M&P 9 does this without any adjustment. Only pistol I've bought that does. I like it. I doubt S&W bothers to polish this feature into each gun. Parts vary. I'm sure some M&P guns do it and some don't. Set it up the way you like. It's simple.

^^^^^^ That's a good story, stick with it^^^^^^

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Criminals don't register guns.

Yeah ginzo, this is an old one. I did get my answer and have used it to answer this same question many times for others.

While it is true that this is not a "feature" it isn't a flaw either. When you insert a new mag, what else do you want the slide to do other than close? So, I fail to see this as a problem.

The reason the M&P is prone to this is simple physics. The slide stop surface area is very small. It also has a spring with a downward bias. Combine these two with a firm mag insertion and the slide will drop every time. Again, the mag should be inserted firmly, not slammed.

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Freedom isn't free.

+1 Your always on top of the game!
I told you I have your notes in my range bag, right? Always give you credit when I pass them along to another newb. (can't afford to pay the royalties)

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Criminals don't register guns.

How hard do you have to "slam" the mag in? I tried this exercise with my MP40C and the slide does not close upon inserting the mag.

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State of Jefferson
Jim

I suspect that weight has a lot to do with the "auto forward" occurrence. I can get the slide to release almost 100% of the time with a full FS mag, the same is not true if I reload with a downloaded mag or with my compact. I always chalked the compact not doing it because of the shortness of the grip not allowing me to do a full push to the base of the pistol (my strong hand cushioned the impact) but I've come to the conclusion that it is weight related. If I reload my compact with a FS mag (that is also full) then I can get the slide to release. Don't know if that's because of the weight of the full mag or if it's because of the longer mag allowing me to seat the mag with full force. Not a big concern because I rarely shoot the compact in competition, and when I do it's a BUG match and the mags are downloaded to 5 rounds (I guess to make it fair to the 5 shot revolver guys ).

P.S. I never "slam" the mag like a number of shooters do, to me that's a double motion that wastes time.

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Minimize the variables

Not all M&P's will do it. It's neither a design nor a flaw.


Full mags exert more pressure on the slide stop than does a partially loaded one. It could be weight, but I think it has more to do with spring pressure in the mag with it fully loaded. Kind of like a Jack in the box. Make sense?

I don't "slam" either, but I am heavy handed by nature.

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Criminals don't register guns.

I try to stay on top, but don't always succeed. Thanks for the credit, but it's really just a compilation of other people's work. I don't remember the last time I had an original thought. As far as "royalties" are concerned, you're not off the hook. I expect a lunch the next time I'm in North Port. Since I find Florida hot and sweaty, and I have no idea where North Port is, it's unlikely I'll be over that way anytime soon.

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Freedom isn't free.

I'm with you, I am slowly becoming able to speak with some authority. I take some input, go test it, then either agree or disagree.

On something I am not sure of, to be fact, I do not comment. But sit back and wait to absorb some more.

As far as lunch, you certainly would be entitled/welcome. As to the fact you may never be in this hot sweaty hell hole, I was gonna treat you to Filet Mignon! To bad, so sad!!!

Now if you happen to show, they got this great place here called Micky D's, it's steak also. I don't think you have them where you are? LOL

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Criminals don't register guns.

Just a note, I was doing the"testing" with a full mag.

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State of Jefferson
Jim

Not all M&P's will do it. It's neither a design nor a flaw.

I know my .40 FS does it, I will check my .40c in a day or 2 and get back with you.

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Criminals don't register guns.

According to the gurus at my LGS, this is the nature of the poly-framed beast. If it's any consolation, Glocks are prone to do the same thing. For the record, I've got three M&P's and none of them have ever released when the mag was inserted. Will it happen down the road? We'll see.

I wish more would do this. Alas, too many just believe what they think "sounds good" rather than test it for themselves.

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Freedom isn't free.

Slide release when mag is inserted M&P9 FS
When you seat a mag in your handgun, the grip angle is 18 degrees and you're probably pressing forward just a bit with the meat of your hand. This means there is some force vectored to push the frame forward. As the frame accelerates forward, the weight of the slide causes it to lag behind a moment until the recoil spring presses enough to move it along. This lag behind in the slide mimics you pulling it back a little and gives an opportunity for the slide catch(not slide release) to fall by it's spring pressure. You can get this to happen in most semiautomatics by hitting slightly forward with the meat of your hand when you seat a mag. It happens a little easier on the m&p for a variety of reasons, one being the rear of the slide stop cutout is angled to reduce local stresses that could cause a crack there.

It's not a big deal and will actually help speed up reloads. Keep in mind, your muzzle should be in a "safe" position and your trigger should be out of the trigger guard until you're ready to fire anyway, so this shouldn't cause anything bad. View it as more of a feature than anything and enjoy.