Smith & Wesson M&P: Malfunction or Feature?

[G60]

There was a thread a few weeks ago asking everyone to list which handguns they had that did the same thing.

It was a really long thread.

[9mmepiphany]

My M&P is right on the edge of dependability...but I'm really working on getting it to do it all the time. It always seems to work during full speed mag changes

The slide only releases with the insertion of a mag if:
1. The slide was locked back by the follower activating the slide stop...I can't get it to work when I manually lock it back.
2. Magazine must be filled...I'm trying to determine if there is a certain number of rounds to ensure it always happens...empty mags won't release the slide
3. Mine requires that the mag be inserted with a full push on the bottom of the baseplate with the heel of my hand...not an issue as I don't ever baby the mag into the magwell.

[iareConfusE]

Not a malfunction, but also not necessarily an intentional feature. It isn't 100% reliable, so don't completely rely on it as your main method of putting the gun into battery.

[ruchik]

My M&P is right on the edge of dependability...but I'm really working on getting it to do it all the time. It always seems to work during full speed mag changes

The slide only releases with the insertion of a mag if:
1. The slide was locked back by the follower activating the slide stop...I can't get it to work when I manually lock it back.
2. Magazine must be filled...I'm trying to determine if there is a certain number of rounds to ensure it always happens...empty mags won't release the slide
3. Mine requires that the mag be inserted with a full push on the bottom of the baseplate with the heel of my hand...not an issue as I don't ever baby the mag into the magwell.

Inserting an empty mag will never release the slide forward, ever. The follower is always pushing the slide lock upwards, which is how the slide locks back in the first place. Just one round in the mag is all you need to make the slide go forward, either by auto dropping the slide or manually releasing the slide lock.

[ZX-10R]

Mine does. I am always aware of it...That is the most important part.

[9mmepiphany]

Inserting an empty will never the slide forward, ever. The follower is always pushing the slide lock upwards, which is how the slide locks back in the first place. Just one round in the mag is all you need to make the slide go forward, either by auto dropping the slide or manually releasing the slide lock.

Brain fart

I meant almost empty. I've tried it with one round and it won't always go, frequency increases after loading two rounds

[carnelianbay]

I have a SW M&P 9mm for over 4 years and have never had this happen.

I do not insert the magazine hard nor have I tried to intentionally accomplish this task so I cannot say that mine is not capable of doing so, but in 4 years having never experienced this would have me wandering...

This will give me something to try at the range next time though, but I am well trained on hitting the slide release when doing mag changes.

^^^ Same here. I was very surprised to find this thread.

[ruchik]

In Magpul's Handgun DVD, Costa explains this very issue in detail. Drive the mag straight into the grip, slide won't go forward. Drive the mag into the grip at a forwards angle towards the trigger, and the slide will drop automatically. Works on an M9 too, and several other guns.

[cindynles]

Brain fart

I meant almost empty. I've tried it with one round and it won't always go, frequency increases after loading two rounds

This makes perfect sense. More rounds in the mag = more weight, more weight = more energy, more energy = higher likelyhood of releasing the slide stop.

[InGrAM]

Damn, mine doesn't do this. :/. But I guess, I haven't been playing hard enough with mine. lol

[jmzhwells]

Just make sure you are not slamming on the ejector, which will brake from slamming in full mags while out of battery. Have seen it happen several times on the 4006 TSW. Not sure where the ejector is on the MP, but if its on the upper left side between the slide and frame, the top of the mag will hit it, causing the ejector to break up. Then you are S.O.L.

[fullrearview]

I have been able to do it with every semi I have fired.

[Sam]

I'd say it's a bug in the system. If it did it 100% of the time then it may be a feature. Mine does not do it 100% of the time and I'm ready if it goes into battery by itself and ready if it doesn't go into battery by itself.

[XDRoX]

I'd say it's a bug in the system. If it did it 100% of the time then it may be a feature. Mine does not do it 100% of the time and I'm ready if it goes into battery by itself and ready if it doesn't go into battery by itself.

It will do it 100% of the time if you put the same amount of force every time.

[throwbricks]

Its physics. The act of forcfully inserting a full mag transfers enough energy to move the slide enough to overcome the friction holding the slide to the slide stop. It's just easier to do on some guns than others. My Glock 19 will do it 99% of the time, but my 5" 1911 hasn't done it once.

^ This. There is no debate here. It is not a feature, it is a fact of design. The slide stop is held open by Friction. Friction is overcome by Force. Force = Mass x Acceleration. Conservation of energy means the Mass of your magazine x the Acceleration of you slamming it home will be transferred into the gun. Enough Force and you will overcome the Friction. The inconsistency of the effect comes from an inconsistency in Force (either the magnitude or direction of the vector), among other factors like how well the follower on your magazine seated the slide stop when it locked it back, etc.

You could interpret it as a design flaw, but it is common in nearly every semi auto.