Software Issue with Glock 43: Inadvertent Slide Lock

[Coal Train]

I've had a Glock 43 for a few years now and have been working on my proficiency with the pistol for it to serve as a carry piece when the Glock 19 is a bit tougher to carry (or I'm being lazy). I initially struggled to shoot the 43 with acceptable accuracy but I have worked through that issue and I am at the point where the accuracy at the 7-10 yard range is acceptable to me.

The more challenging issue I'm having is that I am unintentionally locking the slide back during recoil. This will happen at some point through ~every other magazine. It happens across multiple magazines and loads. I do not believe the issue is a mechanical issue with the pistol. The slide locks back, the rounds are not hung on the feed ramp, and the magazine can easily be ejected. When the slide is released the firearm returns to battery and will continue to function.

I shoot right handed. From what I can diagnose my support hand thumb base/palm (Themar area) is pushing up on the slide lock under recoil and randomly locking the slide back. I am using a "standard" grip, high on the pistol, thumbs forward, support hand thumb on the top side of the frame. This is the same general grip technique I use with all other Glocks and handguns. If I move my support hand thumb off the top of the 43 frame and rest it on the side of the front of the trigger guard the problem goes away. This effectively lowers my support hand grip enough to eliminate activating the slide lock under recoil but it negatively impacts accuracy. And more importantly, it feels weird and I do not want two different grips between the 43 and the 19.

This problem is unique to the 43 for me. I do not have this problem across other platforms (Glock, Sig, HK, etc.) including slim, single stack 9mms like the Shield or the XDs.

Is there another software solution to this issue? I'm certainly open to hardware changes to the 43 as well.

[psalms144.1]

CT - I would strongly suspect the culprit isn't your support thumb, but your strong thumb. I'm having trouble picturing how your support thumb would get anywhere near the slide catch lever. For me, if I don't consciously move my strong thumb "outboard" off the G43 frame, I have issues with inadvertent slide lock. And, I agree, it's specific to the G43 - never had this issue with PM9, P239, 1911, etc...

If you could post a photo of the pistol in your normal grip, that might help us diagnose.

[Coal Train]

CT - I would strongly suspect the culprit isn't your support thumb, but your strong thumb. I'm having trouble picturing how your support thumb would get anywhere near the slide catch lever. For me, if I don't consciously move my strong thumb "outboard" off the G43 frame, I have issues with inadvertent slide lock. And, I agree, it's specific to the G43 - never had this issue with PM9, P239, 1911, etc...

If you could post a photo of the pistol in your normal grip, that might help us diagnose.

Thanks for the response psalms! Support hand thumb is probably not the best description. It's not really the thumb, more the portion of the palm below the thumb, towards the wrist.

I'm usually pretty good about keeping the strong thumb more outboard but that is certainly a possibility. I'm more diligent about it with Sigs so I may be getting lazy with Glocks.

[Doc_Glock]

I understand what you are saying. If it is the meaty part of the thenar emminence causing the problem, you will have to adjust your support hand grip. nother more radical solution is to cut that portion of the slide lock down to a nub and just use an over hand slide release if you want to release the slide.

I had an issue with a Glock 42 not locking back on empty. In this case it was my right thumb and I had to train myself to put the right thumb over the left thumb base rather than against the pistol frame. You may want to try this a bit on the chance that it is actually your right thumb causing the issue.

[lwt16]

I do that too with my G43.

I have to utilize a thumbs down grip with it to keep from locking the slide back.

[Gio]

I do the same thing with an extended slide release with my support hand grip bc of how high and forward I get it on the gun. A standard/flat slide release fixes it for me. If you have an extended release on, I'd recommend trying the standard. You can also play around with your hand position in the gun by adding hogue wrap grip sleeves that have some palm swell to them which will change your support hand position relative to the slide release.

[Coal Train]

I was able to get back to the range this past week and it turns out......my strong hand thumb was causing the problem. When I was more diligent with rolling my strong hand thumb farther away from the slide the problem went away. Looks like I'll be working on some software upgrades in this regard.

Thanks to everyone for their help with addressing the issue!

[Permethrin]

extreme and definitely not something i recommend others do but...

my occasional carry G43 has a tab-less slide stop due to this issue.

[1slow]

I have to put my gun hand thumb on top/behind my support hand thumb to not interfere with the slide stop. Bill Rogers suggested this. This has worked with Glocks and HKs for me. Otherwise I create malfunctions.

[gtae07]

I had the same issue with my new (to me) LC9s, till I figured it out.