Glock slide failing to lock back

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ChristopherG

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The slide on my G17 failed to lock back on an empty mag several times yesterday. This has never happened before in the 3000+ round life of the gun. What has happened a couple of times before, and also happened again yesterday, is this: when I load a new mag from (normal) slide lock position and slap the mag into place, the slide closes on its own, apparently from the jarring of the new mag being seated.

I did put in a new (factory, standard) captured recoil spring assembly yesterday, but I don't imagine that's connected, since the related problem mentioned above has happened previously. But what do I know?

Anyone know what my trouble is? Thanks for the help--
Chris

PS--it's happened with different mags, both normal and reduced cap
 
I am not a gunsmith, nor do I play one on TV, but from what you mentioned it may be magazine related. Advice that I have gotten in similar situations is to check the magazine first. Get a brand new mag and see if that cures it. Usually a worn magazine spring or a magazine follower that is worn down can fail to lock the slide back.

As far as the slide releasing when you insert a new magazine in the gun, just how hard are you slapping the mag in? If the previous magazine just barely causes the slide lock to engage, you may be hitting the bottom of the mag with enough force to jar the slide loose.

I will be very interested to see if my analysis matches those from more experienced people and if we can determine just what is happening in your case.
 
FPrice--
Your suspicion about mags is confirmed--at least it's a reasonable suspicion, that is--by a brief search over at Glocktalk. It's all about worn mag springs with them, and I have to admit to less than perfect mag maintenance, so maybe that's my problem. If it were, I would have expected to start seeing it happen with one mag before others, but maybe not. Other culprits according to Glocktalk denizens are a worn slide stop, me touching the slide stop (I'm not) or limp wristing (I don't).
CG
 
yeah, sounds like springs are the answer. I took it apart, examined the slide stop lever, disassembled and cleaned the mags, and everything is good as can be, so mag springs will be the next thing I try. Thanks for the suggestions.
Chris
 
Did you check for any unusual wear in the slide catch or its notch in the slide?
 
I did look at both. The slide itself is just fine--no marks of any kind where it catches. The little catch portion of the slide stop lever is worn in that it's not black anymore, but I don't know what it looked like new, so it's hard to say if its wear is unusual. Looks okay to me.
Chris
 
Although I'm not expert enough to credibly disagree with the guys on Glocktalk, the suggestion that this is magazine related doesn't seem to make sense...

Before you go trying to fix the problem with new magazines, try slamming the butt of the grip, when the slide's locked back -- with no mag in the grip.

I'd be willing to bet it'll go forward without a magazine in it... That has proven to be the case with some Witnesses I've used or exchanged messages about.

When a mag is full, it should not be in the loop -- there's nothing that should be affecting the slide stop/release, etc.

I've seen similar problems in CZs and EAAs, and the problem there is generally 1) a weak slide stop spring (which is letting the slide stop move when the mag is rammed home), or 2) a worn detent in the slide, which lets the slide ride up over the slide stop. Replacing the slide stop spring often helps, and squaring up the notch in the slide also helps.

If it turns out that it IS mag related, I hope someone here can explain HOW it causes the problem.

I have this same condition with an Witness Sport Long Slide I shoot in IDPA. Its a new "condtion" as it didn't happen in the past. But I shoot IDPA and I "LIKE" the "problem," as it speeds slide-lock reloads.

Is it really a problem? When you slam the mag home, don't you really want the slide to go forward?
 
Walt, in response to your last question, yes: of course, what would be optimal would be if the slide locked back on an empty mag and then slammed forward exactly when I popped a new one in. In fact, I've mystified friends with this trick. But I'm thinking the two may be incompatible, ultimately.

If the problem persists, I may just take a file to the slide stop no matter what it looks like, to sharpen that edge up and see if that helps. It would also be an easy part to replace. Thanks for your input.
Chris
 
Chistopher G,

The possibility exists that the new recoil spring assembly is having an effect on slide velocity and causing your problems.

Are you shooting factory or reloaded ammo?

You might try your factory original spring again to be sure. If you have the same problem, then it is indeed most likely to be a weak magazine spring or worn follower.

Good luck.
 
I still don't understand how a weak magazine spring or worn follower (or the magazine itself) enters into this problem.

The problem as described was the slide closing when it should've stayed locked back as a new, fresh, full mag was inserted. As soon as the new mag was slammed home, the slide slammed shut. It locked back at first, but didn't stay locked back!

When that happens, the follower is way down the tube, so the follower can't be involved. Perhaps the mag spring is involved, but I don't see how.

Can somebody/anybody explain the role of the magazine in the problem described? I'm really trying to understand what's going on here, and most of the suggestions seem inappropriate.

(I said the suggestions "seem" inappropriate. I appreciate that they may, in fact, be a correct response to the problem, but I just don't see how. I'd like to understand what's happening, so that the "fix" makes sense. A lot of the recommendations on gun forums are like "old wives' tales" -- some work, some don't. Maybe someone can explain.)
 
The problem of the slide releasing when a full mag is slapped in the gun is a NON existent problem.
This is because that Glocks are designed to do this. [As I have been told talking to Glock reps.]
All my Glocks release the slide in this manner.
If you don't want to load the gun, then DON'T put a loaded mag in it... :rolleyes:

As for the slide NOT locking back.
This has to do with the mag springs.
If this is a problem for you (for me its not, some mags lock, some don't. NEVER shoot dry a gun [Good tactic]) then eighter change to a new spring, or take out the ones you have, and stretch them a little. I'm talking about maby 3-4" from relaxed, and then let them go back. They will probably grow like 1".
You can also stretch the spring a little more in the front top, so that there is more force where the follower contacts the slide lock.

I am a gunsmith, and I play one on TV (not really) ;)
 
Not really. You omitted the following sentences...

He wrote:

The slide on my G17 failed to lock back on an empty mag several times yesterday. This has never happened before in the 3000+ round life of the gun. What has happened a couple of times before, and also happened again yesterday, is this: when I load a new mag from (normal) slide lock position and slap the mag into place, the slide closes on its own, apparently from the jarring of the new mag being seated.
Click to expand...
When you read the whole thing, the problem seems different...

If the slide were failing to lock back on an empty mag, I'd agree with the mag spring/follower diagnosis. But it seems that he's saying its not STAYING locked back when he inserts a new, full mag.

Am I reading his statement wrong? Or is the original writer talking about TWO SEPARATE PROBLEMS?

Most of the solutions offered here address the "failure to lock back" problem, but ignore the "when I load a new mag from (normal) slide lock position... the slide closes on its own." That's the part I was responding to. A good follower and strong springs won't help wit the second part of the problem.
 
Well, then, I agree with the follower/mag spring diagnosis.

That said, however, when I had a Glock 17, it didn't slam shut when I inserted a new mag. Wish it had. I've seen it with other Glocks, but didn't know it was a DESIGNED feature. (Thought it was one of those unintended benefits for SOME guns.)

(Afterthought: if the slide automatically closing with insertion of a new mag is a design feature, why isn't it universal, and why do they offer extended/oversize slide releases? Isn't that one of hte features of the G-34? Had one on my Glock, installed by a buddy who was a Glock Armorer...)

It was apparently something the shooter had not experienced previously -- it was an unexpected behavior.
 
Last edited:
Well, I went to an IDPA shoot today, and the problem did not reoccur. What I did last night was a two pronged attack on the problem: first, ordered some +10% mag springs from Glockmeister; then, as a more immediate measure, took my mags apart (for the first time; this may have been part of my problem, yes?), cleaned them well, and kind of 'stretched' the springs for short-term rejuvination. This appears to have taken care of it for the nonce.

As for the slide closing upon inserting a new mag, that didn't happen today, either (though we only had a couple of reloads from slide-lock)--but I'm intrigued to hear that I might actually hope for this to happen regularly. I'm perfectly willing to set the mag with a little extra pizazz, in the hopes that I could make this a regular function, 'cause it really is smooth when it works.

And, I won my division today. :) it's only Marksman, so nothing to write home about, but this little problem will hopefully just be one more small hurdle on my climb to some kind of actual proficiency ;)

Thanks all for your suggestions.
Chris
 
I am not sure if you have replaced all of your Glocks springs. I had a similar problem with my Glock, and it meant it was time to replace springs. I find that a sign to replace all my springs, unless I want malfunction practice:eek:
 
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