[Bruce in WV]

I use nothing but factory GLOCK magazines and most are like new or excellent condition. All are 9mm.
I use these interchangeably in several different model guns, G17s, G45, and G26, all with full power factory cartridges. Occasionally the gun(s) will not lock back on an empty magazine. This could be fatal and is unacceptable.
What is the cause, and what is the cure?

 

[mtstream]

Test the mags by leaving them empty - insert into gun and rack the slide hard and quick. If it locks open, the mag and slide stop lever pass.

The most common cause is the shooter’s thumb holding the lever down, even if it’s just barely enough to partially interfere. If all the mags check out OK, pay attention to your grip, especially towards the end of a string of fire.

I’m assuming the mags have not been modified (extensions). The spring has to have enough force to actuate the lever. Start marking any mag you have an issue with to see if it starts being consistent.

 

[Bruce in WV]

Test the mags by leaving them empty - insert into gun and rack the slide hard and quick. If it locks open, the mag and slide stop lever pass.

The most common cause is the shooter’s thumb holding the lever down, even if it’s just barely enough to partially interfere. If all the mags check out OK, pay attention to your grip, especially towards the end of a string of fire.

I’m assuming the mags have not been modified (extensions). The spring has to have enough force to actuate the lever. Start marking any mag you have an issue with to see if it starts being consistent.

Good information! Odds are my grip: this started after a recent class to learn to use RMRs properly, and coincidentally, the instructor changed my grip to much higher right and left thumb positions. I will check every mag without using a "shooting grip", mark any that don't pass that screening and start monitoring my grip with the rest.
Thanks!

 

[uzimon]

Hardly fatal

 

[Taterhead]

Good information! Odds are my grip: this started after a recent class to learn to use RMRs properly, and coincidentally, the instructor changed my grip to much higher right and left thumb positions. I will check every mag without using a "shooting grip", mark any that don't pass that screening and start monitoring my grip with the rest.
Thanks!

This is why I like Bob Vogel's grip. It is very high on the gun but the support thumb rotates down onto the support hand giving some presure and it avoids interference with the controls.

 

[Nanuk]

If it is not the mags, it is the shooter.

 

[cciman]

This has a twin condition: Slide locking back prematurely.
Both have 2 common causes:
Shooter thumb bopping the lever on recoil
Poorly installed, broken or worn spring on slide stop lever.

Can be more likely with "extended" tactical levers.

One other condition-- worn or weak mag springs, or bad follower, or aftermarket mags, can prevent slide from locking back on empty. Thumb is still the likeliest culprit.

 

['Ol Grandad]

I use nothing but factory GLOCK magazines and most are like new or excellent condition. All are 9mm.
I use these interchangeably in several different model guns, G17s, G45, and G26, all with full power factory cartridges. Occasionally the gun(s) will not lock back on an empty magazine. This could be fatal and is unacceptable.
What is the cause, and what is the cure?

Any chance you're a lifelong 1911 shooter and you're somewhat new to GLOCKs? Just wondering 'cuz the grip for each is quite different.

 

[Z71bill]

I was having this issue with my P365 - I figured it was weak range ammo -

Then I had the slide not lock back while using +P ammo.

I am pretty sure my thumb is hitting the slide catch lever.

I should have know - it was happening more at the end of my shooting - I thought maybe gun was starting to get dirty - but more likely I was getting tired and lazy with my grip.

 

[ActanonVerba70]

I use nothing but factory GLOCK magazines and most are like new or excellent condition. All are 9mm.
I use these interchangeably in several different model guns, G17s, G45, and G26, all with full power factory cartridges. Occasionally the gun(s) will not lock back on an empty magazine. This could be fatal and is unacceptable.
What is the cause, and what is the cure?

Probable Causes:

1. Improper hand position
2. magazine issue

ETA: reread @mtstream post. I echo his assessment.

 

[Bruce in WV]

"Any chance you're a lifelong 1911 shooter and you're somewhat new to GLOCKs? Just wondering 'cuz the grip for each is quite different."

Yes! First thing the instructor noted was my 1911 grip left over from 50 years of bullseye shooting. Focusing on self defense with 9mm Glocks has required a number of changes.

Reviewed the Bob Vogel videos and have begun dry fire practice following his example.

The magazines checked out OK.

 

[Leviathan]

Grip. 100%.

Of all things, about 5 years ago, I watched the Art of the Dynamic Handgun with the now famous Chris Costa and Travis Haley, and learned I had been gripping a handgun incorrectly for 39 years.

Really.

Now keep in mind I was an excellent shooter, but something was off. I modified my grip as Mr. Haley demonstrated and Viola' massive immediate improvement.

have a shooting buddy or instructor watch your grip as you fire. If the gun squirms or hands come apart, you need to evaluate how you build your grip.

Good Luck!

 

[cciman]

The majority of shooters are self taught, and often don't take feedback well. Many long time shooters have been practicing bad habits and poor fundamentals.

Training and coaching is a game changer. Being trained early in shooting is better than later when habits get ingrained.

 

[Callducks7]

Sometimes its just a bad slide, slide catch interface. Recently when I had this issue I simply swapped catches between two G17 and both worked afterwards.

 

[jacala]

I solved that problem a longggg time ago.
I got rid of the extended slide stops on all of my Glocks. Put the small (original ?) ones (back) on and I can continue to use the correct high grip and have no problems.

 

[mileslewien]

Having the same problem with brand new gen 5 glock9. Also shooting my dad’s glock19 and did not have the problem, tried every combination of different mags, different ammo, my dad and brother both shot mine and and had the same problem. It’s not our grips, and it’s brand new

 

[mtstream]

If you insert an empty magazine and rack the slide, does the slide lock back?

 

[mileslewien]

Yes, it does stay back when I rack the slide with an empty mag. I actually discovered that I was wrong about it not being the grip, in a way. I am left-handed, as is my dad, and my brother is right-handed. I wish I could post video but the right side of the slide release is very loose and when I touch it even very lightly it wiggles down and up, while on the left side it is very tight how I would consider normal and does not move just by barely touching it. So when I shoot right-handed it doesn’t have that problem, except for one of the times that my right-handed brother shot it where it did the same thing. When I shot it right-handed with my thumbs purposely covering the left-side slide release, it functioned properly and the slide locked back. For some reason the slide release on the right (the left-handed one) is very loose and sensitive and the only way to shoot left-handed and not have that happen is to purposely keep my thumbs away and shoot improperly (as far as I know, my grip technique is from youtube videos by Mike Glover where I point my offhand thumb along the barrel at the target). Even when not touching the slide release, if my thumbs are too close, the recoil will make it touch the slide release and that is enough to make it not stay back. I’ve shot many Glocks and never had that problem, seems like just my luck that when I buy my own it is somehow ultra sensitive and I also noticed that there is about 0.5mm space on the right side between the slide release and the body, while the left side slide release is firmly tucked against the body. I’m wondering if it’s just a defective or poorly installed slide release as on the Gen 5 it seems that it is just one piece that loops around and makes it ambidextrous. I obviously don’t know much about it, so any help or ideas on what to do about it would be greatly appreciated

 

[mileslewien]

Idk if I’m allowed to post my phone number and if not I apologize just let me know and I’ll delete it, but if anyone wants to see the video that shows what I mean it is 2533043643 just say you’re from Glocktalk and wanted to help.

 

[mcvoss]

Went to shoot my 42 right after I bought it. Damn thing would not lock the slide after last round. I'm right handed by the way. After getting frustrated I tried shooting left handed, yep slide locked back everytime after last round.
Minor adjustment to my grip right handed and no more problem.