M&P's Auto Forward

[clcdawg]

My M&P 9 fs does this sometimes. I don't really like that it does though.

 

[Gauger]

I have a 40 and 40c. I have had the full size for 6 months and the compact for two weeks. The full size started doing this about a month ago. I have around 1200+ rounds through it. The compact does not do it but I only have 250 rounds through it so far. I do not slam the magazine but I do close it with some force. It doesn't really bother me other than in a high stress situation the more repetative the your actions are the less likely you will have trouble.

 

[njl]

It happens with a lot of different brands of pistols. My opinion is it's fine if you are playing games, but I wouldn't like it in a self defense situation and the reason being is this. Whether this will happen with M&P's I don't know, but I had an officer tell me his dept issue Sig P229 40s&w was malfunctioning. He said it wasn't chambering a round when inserting a partially loaded magazine during a drill. We were able to replicate the issue easily and what was happening was he was inserting a 1/2 loaded magazine with enough force to cause the rounds to compress the magazine spring and in turn when the slide went forward automatically it wasn't able to strip off the top round. He had to recycle the slide to chamber a round. Like I said, I don't know if this will occur with the M&P mags, but it's something to keep in the back of your mind...if it should just go "CLICK"

Sorry about the necro-thread, but I've been googling for a couple days trying to find anyone else talking about this issue. I've only just recently encountered my Glock 19 doing this (failing to strip the top round) when slamming in 15 round mags loaded to 10 at a slide-lock reload. i.e. The slide does close...but the chamber is empty. Even with brand new mags, it'll do this.

Another shooter at the match where I just had this happen twice told me to use 10 round mags. I'm curious if there are any other fixes other than use full mags (can't in IDPA) or insert more gently and release the slide manually. I suppose maybe Wolff extra-power mag springs?

 

[Ray1970]

I've run a Glock 19 in IDPA quite a bit. Always use the fifteen round magazines downloaded to ten rounds. Never experienced the phenomenon you are describing. I'm thinking something might be going on with the gun itself. Might break it down and see if there's anything obvious.

 

[shawn mccarver]

Yet, some Spec. Forces people I know that now do tactical pistol training for LE and civilians count on the auto forward ability of just about any modern semi-auto pistol to get sights back on target as quickly as possible.

Just saying.

All of the special forces people I know (none) would say that it is a TERRIBLE idea to depend on what a few arm chair warriors believe to be a designed in feature no matter how many people say otherwise. All of the regular lifelong shooters that I know (many) agree that it is terrible training to train someone to depend upon the slide to "close itself" when it is not really designed to do that.

If you ask me, the design is defective for allowing this to happen.

 

[gonerydin]

The slide stop of M&P 2.0 is redesigned to prevent this phenomenon. My M&P9 has the auto forward "feature" and I don't particularly like it.


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[njl]

I've run a Glock 19 in IDPA quite a bit. Always use the fifteen round magazines downloaded to ten rounds. Never experienced the phenomenon you are describing. I'm thinking something might be going on with the gun itself. Might break it down and see if there's anything obvious.

What sort of ammo do you generally shoot? In all cases so far my 19, it's been two varieties of my own reloads using either 147gr Montana Gold or 149gr flat point hi-tek coated lead (H&S).

 

[Arik]

Design isn't defective. It's simply something that happens when the mag is inserted hard enough. I've had it happen on every semi auto I've owned. And on Saturday it happened twice on a new gun

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[photoman]

Any semi-automatic pistol with a slide stop spring that is strong enough will do this. One can use a weaker slide stop spring to prevent this but then the risk becomes having a gun that will lock open before the magazine is empty.

The design/shape of the slide stop notch on the slide plays a part also.

In my opinion, a properly designed and maintained semi-automatic pistols should NOT do this.

 

[CB3]

Any semi-automatic pistol with a slide stop spring that is strong enough will do this. One can use a weaker slide stop spring to prevent this but then the risk becomes having a gun that will lock open before the magazine is empty.

The design/shape of the slide stop notch on the slide plays a part also.

In my opinion, a properly designed and maintained semi-automatic pistols should NOT do this.

The variances in slide stop spring pressure certainly will affect whether the slide auto-forwards. For me, however, the key determining factor has been the amount of friction between the slide stop and the slide notch.

Lots of friction = a stop that is difficult to disengage, even with a relatively new or stiff spring. Often new stops, commonly a stamped metal part, will have a fairly sharp ridge that engages the slide, making them most impossible to release unless the sling shot method is used. When the mating metal surfaces wear, reducing friction, auto-forwarding is more likely.

Most slide stops on semi-autos work the same way, the new 2.0 M&P being a notable exception.

So, here's the fix:

You don't want it to auto-forward? Use some 400 grit wet/dry sandpaper and lightly rough up the two mating surfaces.

You do want it to auto-forward in a manner you control? Polish the stop's engagement surface first to reduce friction, just a little at a time. Add some roughness if you screw up, or buy a new (cheap) stop. Avoid working on the slide's notch, although the same polishing principles apply.

For me, a properly adjusted slide stop will function in numerous ways to release a locked slide (Thumb, finger, slingshot, auto-forward). This means I polish the stop engagement surfaces on all my pistols of all makes before I ever shoot them, and I have been doing so for over 25 years. They all function the same, and I control it, not some haphazard factory slap-together procedure with varying spring pressures, tolerances, and amounts of friction based on mass produced parts and speed of assembly. All custom guns have adjusted slide stops.

Training is the issue more than mechanics. Any procedure or mechanical part can fail. You must have an ingrained plan "B" ready to go as a backup. Whatever method you choose as your primary for releasing a locked back slide, you need to train for an alternate. If you release the slide and expect a bang and get a click, tap-rack-bang immediately. The problem could be any of a number of things, with not picking up the top round from the mag being just one of them.

If TRB, doesn't work, go to your next trained procedure, usually a complete reload.

I have found auto-forwarding to be very fast, simple and reliable for me when my stop/slide interface is adjusted correctly. It is my primary means of releasing my slides from lock. However, I use other methods to release a slide to stay familiar with them and as a backup.

As far as the claimed reproduceable failure to pick up the top round in a downloaded mag, I have never had it happen. Running the mag home hard seats it positively--a good thing. This seating of the mag jars the slide enough that the stop immediately drops. The laws of physics seem to favor the idea that the rounds in the mag would want to continue in the direction they were traveling, i.e., upward. I don't see how they would do the opposite, i.e., compress down into the mag so the slide would not pick up the top round.

On the other hand, if in a two-step procedure, the downloaded mag is inserted and locked in place with the slide open, and THEN the gun is brought DOWNWARD and hits a hand or other object at the base of the grip to jar the slide stop loose, that could send the rounds down into the magazine and the slide could miss the top round. This wouldn't happen with a fully loaded mag, or a mag spring stiff enough to prevent such compression, either from being new or because of having enough rounds in the mag to prevent it. It also doesn't happen with the single step sharp insertion method I use.

Just because I have not experienced the problem does not mean others have not either. I look forward to being educated with some logical explanation.

 

[njl]

Last night I tried reproducing the problem at home, doing slide lock reloads with one of the mags I'd used at the match loaded with 9 rounds of the ammo from the match and the top round being a dummy (same 147gr Montana Gold bullet, but no powder or primer). I slapped mags into the G19 until my hand was sore, and couldn't make it happen.

I tried again tonight using an older mag that I know has a worn/shorter spring, and again, slapped the mag into the gun until my hand was sore...still couldn't get it to auto-close on an empty chamber.

I don't know what I'm doing differently...but it's done it 4 times at the range after live firing to slide lock.

 

[CB3]

Could it be that your mag loading stroke was bringing the gun DOWN onto the mag vs. pushing the mag UP into the gun?

I reload with the gun at chin height so I can see it and the target. The gun stays still. I rip the empty mag out with my off hand, drop it or stow it, retrieve the loaded mag and smack it up into the gun. The slide auto-forwards immediately. I acquire a two handed firing grip and go back to work.

If the slide does not auto-forward, my off-hand (Left) thumb hits the stop tab to release it on the way to acquiring the firing grip.

I use the hand-over sling shot method for all malfunction procedures.

 

[Smakmauz]

I would concentrate more on the slide catch lever itself as was said in a previous post. It's not the magazine springs or followers that have an effect on disengaging the lever...only pushing it up on an empty mag. Once the follower engages the catch, the pressure from the recoil spring keeps it open until released onto either no magazine or one with rounds compressing the follower so as not to engage the slide lock lever again. The area on the back of the lever where it locks into the slide is probably worn so the mating surfaces aren't creating enough friction to stay latched when slamming a new mag in place. This can be further exacerbated by a weak slide lock caused by a weak magazine spring or a follower binding up. What I mean is if the follower only sort of half way engages the slide lock by not sending the lever fully into the receiving pocket on the slide then the lock up is already weak. Then if you slam a mag in, that lever is gonna pop right out the socket.

So, get a new slide stop lever, disassemble and clean your mags and lightly lube the followers then check your silde stop engagement by inserting an empty magazine and pulling back the slide slowly until it clicks into place. It should shoot up into the notch in the slide with a nice solid click. Then do the same again only this time pull the slide back as fast as you can.

If you still have problems after that then check the notch on the slide where the lever catches and maybe do what one of the other posters talked about with roughing that up just a touch with some 400 grit or something like that. I'd be willing to bet you won't have to go that far though.

Oh, and also make sure that no oil or grease is on the mating surfaces between the stop and the slide.

 

[ThrowinRocks]

Really...I wonder why, then, they made it external, protruding, and ambidextrous.

As stated above. Slide stop not a Slide release.

All of my 1st gens do it. I would consider it a feature but if you can't keep your finger off the trigger when reloading then it becomes a dangerous operation.

 

[CB3]

As stated above. Slide stop not a Slide release.

All of my 1st gens do it. I would consider it a feature but if you can't keep your finger off the trigger when reloading then it becomes a dangerous operation.

If you can't keep your finger off the trigger while reloading, EVERY reloading operation is dangerous.

 

[ThrowinRocks]

Yeah, Sorry I didn't put EVERY in my reply. LOL

 

[njl]

Could it be that your mag loading stroke was bringing the gun DOWN onto the mag vs. pushing the mag UP into the gun?

It's possible. It's probably a combination of upward force on the mag and downward with the pistol. The easy solution, which I'll practice at the range and use for future matches, is use 10rd mags for reloads...but I'm still curious to figure out why this has only happened so far at the range when using the downloaded 15rd mags.

 

[SATX]

Were the guns designed this way or is it just a fluke?

Personally I like it and I can count on both guns auto forwarding. Makes things very fast on reload. What is your opinion?

Fluke or not, I always liked it on my M&P's as it makes for a faster reload, one less step.

 

[TX-Dennis]

Too bad the magazines don't click in securely with a gentle push and a click that sounds like high quality machinery - like my Taurus does.



I'm kidding, of course . . . but the Taurus magazine release does feel (and sound) elegantly well made when the magazine seats with a gentle push. It's unlike any other pistol I own in that regard - Smith, Ruger, CZ, Sig, TriStar, Bersa all require more force and sometimes auto forward if enough force is used.

 

[SoCalDep]

As stated above. Slide stop not a Slide release.

All of my 1st gens do it. I would consider it a feature but if you can't keep your finger off the trigger when reloading then it becomes a dangerous operation.

...And as I've said many times on this forum before...

You can call it what you want. It is a slide release. It releases the slide. It was designed to do it regardless of what some lawyer wrote in a manual and regardless of what some internet commando says.

The auto-forward is not a feature, the pistol was not "designed" purposefully to allow this, it encourages bad habits and it was disliked enough that it was one of the major changes to the 2.0 version.

If you can't keep your finger off the trigger while reloading then holding a pistol is a dangerous operation. (And-- Now I see CB3 beat me to that observation)