M&P9 "issue?"..or is this normal?

[btg3]

from page 16...

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.

The "automatic" slide closure has been experienced with my M&P at and I've wondered about it.

If this is not designed to be a feature, then the slide lock is slipping. Why?

Possibly due to wear and, if so, will repeated slips on the locking surfaces generate additional wear to the extent that it become difficult to keep the slide locked open? Time will tell, but I don't think so because whether the slide is closed by seating a mag or using the thumb release the same locking surfaces are involved -- by design.

Or, perhaps the cause relates to whether each gun has oil/lube on the lock surfaces. Owners could test that theory.

Or it may be manufacturing variation.

Pondering this further, I got out my M&P and tried seating a mag into the pistol multiple times with increasing force. With an empty mag the slide remained locked (because the follower pushes up on the slide lock and keeps it locked). With a loaded mag, the rounds depress the follower and as the mag is seated more forcefully, there is a point at which the lock will release the slide.

Next question is whether the force of seating the mag is actually causing the slide lock to slip, or is producing a rocking motion of the gun that is akin to pulling the slide back and releasing it. I tried various techniques, but ended up inconclusive.

In summary, the more forcefully the mag is seated, the more likely the slide will release "automatically". Lubrication may be a factor.

 

[TechBrute]

Oh no! Not "ready to fire"!! Whatever will we do?!

 

[9teenEleven]

While, sure, most brands will do this if you jam the mag in, the M&P doesn't really require much force at all. A standard mag insertion for most guns will result in a loaded round with the M&P. Like I said before, I like the "feature" on this gun as it makes reloads really fast, but I also agree with the comment that one has to train with their guns to learn to safely incorporate their behaviour in application.

 

[LNK]

My 9FS does this only if inserting the mag with some vigor. If you just slide it in, mine does not. Don't see it as a negative at all. Why insert a mag if you are not making the gun ready to fire? If you don't want a round in the chamber, let the slide go into battery before you insert the loaded mag.

LNK

 

[Manco]

If this is not designed to be a feature, then the slide lock is slipping. Why?

Well, slide locks aren't typically all that secure to begin with, being spring-loaded to UNlock (since that is their default state when your thumb or the follower isn't pushing up on them) and held only by friction--even a sear can slip under shock (hence the need for safety mechanisms), and those are spring-loaded to lock. Slide locks are only meant to do a reasonable job with a very basic design under nominal conditions. This is why the issue at hand can occur with virtually any pistol design, but the question is why some individual pistols (of any make and model, from everything I've heard) have slide locks that slip so readily. There could be a number of potential reasons, depending on the individual pistol.

Possibly due to wear and, if so, will repeated slips on the locking surfaces generate additional wear to the extent that it become difficult to keep the slide locked open?

That could happen, I think, but then again some pistols do this right out of the box, so the probable causes are either parts that are on the opposite ends of their tolerances or defective parts.

Time will tell, but I don't think so because whether the slide is closed by seating a mag or using the thumb release the same locking surfaces are involved -- by design.

In both cases, parts are sliding against one another, which causes wear. The only way to avoid this, assuming that magazines can be inserted without causing the slide lock to slip, is pulling the slide back to unlock it. If you cannot insert a magazine without the lock slipping at all, then you might want to have your gun checked (it may need a new slide lock spring or some reprofiling of the notch).

Or, perhaps the cause relates to whether each gun has oil/lube on the lock surfaces. Owners could test that theory.

I always put a tiny dab of grease on the contact surfaces of the slide lock, and my M&P40 has never slipped; if it did, then I'd stop doing that because lubrication would seem to make it more likely, but it hasn't been an issue for me. I suppose my gun's slide lock would slip if I applied enough force when inserting a magazine (almost anything can be accomplished with the appropriate amount of force ), but I've never managed to do so, even when slapping them in during reloading drills.

Or it may be manufacturing variation.

Probably. Imagine a slide that runs on the high side paired with a slide lock lever that's on the short or low side--that may just be enough to make the slide lock mechanism more sensitive to shock than usual. Then there is the notch to consider, as a flaw in its machining could change the angle at which the slide lock lever engages it, resulting in insufficient friction to keep the lever in place.

Next question is whether the force of seating the mag is actually causing the slide lock to slip, or is producing a rocking motion of the gun that is akin to pulling the slide back and releasing it. I tried various techniques, but ended up inconclusive.

It could be the latter, as it wouldn't take much--a slight reduction in pressure on the slide lock is all it would take for the spring to pull it back down, releasing the slide. It's hard to tell because the slide doesn't even have to move noticeably.

In summary, the more forcefully the mag is seated, the more likely the slide will release "automatically". Lubrication may be a factor.

Yes and yes, I would think. To a degree this is normal for semiautomatic handguns, but what's not normal or intended behavior is for the slide lock to slip no matter how gently you insert a magazine. This is not dangerous in and of itself, so nothing needs to be fixed if one is satisfied with how one's pistol functions (even considering the accidental slippage a feature), but personally I'd be concerned about whether it can eventually lead to failing to lock the slide back when the magazine is empty (even with the follower pushing upward), and I want to have that particular indicator. In general, I require a properly functioning pistol, anyway, or at least a thorough and conclusive understanding of why an individual pistol is behaving abnormally (which can be for various reasons even for the same behavior).

Oh no! Not "ready to fire"!! Whatever will we do?!

Just put the gun down gently, and tell a police officer or teacher so they can take another evil gun off the street, mmm-kay? You did nothing wrong--everything will be alright. Feel better now?

While, sure, most brands will do this if you jam the mag in, the M&P doesn't really require much force at all. A standard mag insertion for most guns will result in a loaded round with the M&P.

It depends on the individual pistol. I've heard plenty of stories, but I've never personally handled an M&P (and I've handled and shot several at least) that would do it with normal magazine insertion force.

 

[RancidSumo]

Mine does it but only if I put the mag in with some force. Not excessive force but what is typical for a reload if you are actually going for speed and not just sliding gently.

 

[papa_bear]

Does this happen with one less round in the magazine?

 

[RancidSumo]

I shoot with five rounds in the mag fairly often and it still sends the slide forward.

 

[Remo223]

I don't have an M&P or a glock on me at the moment, but my S&W model 4006 won't do it no matter how hard I slam it.

 

[TechBrute]

Remo, there needs to be a simulateous forward motion toward the end of the insertion, as well as upward motion. It's not just about how hard it is done. Also, doing it with an empty mag doesn't work, in case you were doing that for safety. As long as there is one round in the mag, though, it won't activate the slide lock.

 

[Remo223]

I see, I was doing the motion correctly, but with empty mag. try again in a little bit.

 

[Remo223]

that works, thanks

 

[TechBrute]

I actually practice that technique. It doesn't put any more wear on the slide lock/release than if you used your thumb to press down on it to release the slide under pressure. Some people advocate not using the slide lock as a slide release, I guess for reasons of wear, but instead limiting yourself to pulling the slide back to release it. As for me, I've been doing that for years, and there is no more wear noticable on my primary pistol than the identical backup pieces I keep around.

 

[LawofThirds]

My M&P 45c does it. But it's not really in how hard you put the mag in, but how. If it's dead center and lined up with the gun straight on, it won't do it, no matter how hard you slam it in. But tilting the mag slightly forward and to one side does it every single time (which is what you're doing when your muzzle is up and you're sliding in a magazine with your offhand).

Personally, I don't mind it, but I don't count on it.

 

[tactidrool]

Some people advocate not using the slide lock as a slide release, I guess for reasons of wear...

That may be one reason. Another reason I've heard is because when the slide is locked back, it is not always at its fully extended position, and so there is a chance, albeit slight, that when you release the slide it will not correctly chamber a round, so it's better to be in the habit pulling it all the way back and releasing so the slide can get its full motion to chamber the round.

 

[RSVP2RIP]

Quote:
Some people advocate not using the slide lock as a slide release, I guess for reasons of wear...

That may be one reason. Another reason I've heard is because when the slide is locked back, it is not always at its fully extended position, and so there is a chance, albeit slight, that when you release the slide it will not correctly chamber a round, so it's better to be in the habit pulling it all the way back and releasing so the slide can get its full motion to chamber the round.

I thought it was because the slide lock was a fine motor skill and yanking back with the hand over the top of the slide was not.

 

[jlott00]

it wont do it unloaded. And im not using excessive force.

My main concern was it not chambering right.

sounds like its common

 

[newbuckeye]

I think the "WARNING" posted in the owners manual is more as a "heads up" than "Hay, we have a flaw in our product". A pistol is like any other tool. Be familiar enough with it to be proficient and effective. I guarantee, in a SD situation and you run it to slide lock, you will want a fast re-load.

 

[bruzer]

In my opinion the Warning explains the possible feature of the gun and they are making sure the owner is aware of it. We can nit pick all the wording of the Warning but to me if your gun is doing it, it is absolutely normal and not worn or broken or has any problems. So you lucky dawgs with your M&P's get out there and practice your lightening fast magazine changes.
Mike