It happens from time to time. In the over 20 Glocks I've had in the last 25 years, a couple of them did that. Just get another one.

 

That same pin will walk on my 17L. It doesn't do it often, but it does do it. I just push it back in and keep rollin'.

 

That's the Locking Block Pin.

I see you have an aftermarket Magazine Catch. What else has been altered, or disassembled and put back together on this pistol?

The diameter of the steel LBP is thicker at both ends than it is in the middle. Does that describe the LBP you are using?

The Slide Stop Lever has a wire spring that curves backwards and runs UNDER the LBP. Does the end of that SSL wire spring run UNDER your LBP? A very common but serious mistake made by amateur Glocksmiths is assembling the frame with the wire spring ABOVE the LBP. In addition to creating inadequate SSL spring tension which may cause the Slide to prematurely lock open with rounds still in the magazine, that also removes the tension that the SSL wire spring exerts under the left side of the LBP. Without that SSL wire spring tension under it, the LBP is much more likely to walk out during firing.

That's my preliminary diagnosis. The cure is sliding the LBP right until the SSL wire spring can be moved under the LBP. Then center the LBP and see what happens next time you are at the range.

FWIW, there are two other serious assembly errors commonly made by new Glock mechanics:
1. Slide Lock (not Slide Stop) installed backward in the frame, with the groove at its top facing forward. The groove at the top of the Slide Lock MUST face to the rear.
2. Trigger Spring hook where it connects to the Trigger Bar is canted off to the left or right side, rubbing between Trigger Bar and the inside of the Trigger Mechanism Housing. The Trigger Spring hook should lie straight up and down in its groove at its Trigger Bar attachment point. (This issue occurs most often in Gen4 pistols and post-2010 Gen3 pistols, which have an improved TS attachment point on the Trigger Bar.)

All three of these errors may exist simultaneously and still allow the pistol to appear functional. I always check for these three major errors whenever I get to inspect a Glock frame. It takes about 30 seconds.

Also...if this G19 serves any serious purpose as a weapon, replace all aftermarket junk with proper OEM parts.

 

That magazine catch has been the only thing replaced on the gun, I’ll check out all those other points you brought up, thank you.

 

I've had it happen on high mileage G33. Get another OEM pin. No big deal. Also, I agree with Mike-M's last sentence.

 

I had the same problem with a well used police trade in G22 I bought last year. Took it to the mothership in Smyrna and the armorer replaced every part in the pistol except the barrel, slide and frame. Came back with the old locking block and a new one to show the difference. The old block had stretched according to him.
Now the pistol functions like new.

 

^^^ Likely the hole "stretched" / got oblong from use.

OP if a new pin doesn't do it, can apply clear nail polish to one end before fully seating it in, or a new locking block apparently

The nail polish has held in a pin for hundreds of rounds now, a new pin didn't correct it so it's likely the locking block hole is my guess

 

^^^ Likely the hole "stretched" / got oblong from use.

OP if a new pin doesn't do it, can apply clear nail polish to one end before fully seating it in, or a new locking block apparently

The nail polish has held in a pin for hundreds of rounds now, a new pin didn't correct it so it's likely the locking block hole is my guess

I had one of these a while back. Was talking to fastbolt about it at one point, and he suggested replacing the locking block, which solved the problem. I think I had tried multiple new pins with the block. And the block probably had over 100k, so to paraphrase fb, I got my money's worth.

So ya, it's likely the relationship between pin and block, for one of several reasons.

One other thought is to make sure the slide stop is properly engaged in the pin's groove. That should happen pretty much automatically. But depending on specifics, I guess the pin could want to consistently walk in the direction forward of that engagement point.

With Glock parts in general, it's usually a slam-dunk to just replace OE components when this stuff happens. So if you don't have a bunch of equity in them (a really great trigger bar, for example) that may be the easy solution.

If you think about how that whole assembly works, it all should be very stable and consistent if the stop is properly engaged in the groove and the pin is reasonably concentric with the block's bore.

Looseness of fit between the pin and frame should not be a problem. I have some frames that are very loose, with no walking at all.

 

I have a Gen4 G17 with about 5,000 rounds through it. It's a GSSF pistol and there are no non-OEM parts in it. Still, that locking block pin will occasionally walk out to the left side when I'm shooting. Just push it back in, but make sure you're using a tool or something to push it far enough. I've found on mine that if I just push it back in with my finger that it usually doesn't pop back in far enough and will quickly walk back out.

 

I have a couple that are a little loose.

Install pin.
Place a drop of blue Loctite over the end of the pin and let it soak in for a few seconds.
Repeat on other side.
Wipe off excess.

Pin will not walk out.

 

Glock has started telling armorers to double check that the locking block pins are "centered" in the frame, or else they might "walk". (Just checking to push on each end so they're "evenly" recessed in the hole, from each end, is what they described. Using a rear corner of the Glock pin punch handle reaches just far enough into the frame holes on each side to do the trick, according to Glock.)

At one time Glock suggested to LE armorers that the LB pin was replaced every 5,000 rounds in .40 models. Whenever I inspect a Glock for someone, or my own Glocks, I check to make sure LB pins in working guns roll flat and the ends aren't peened (the "dumbbell" ends are impacted by the locking block during recoil).

If this were happening to a well-used gun, I'd also suggest trying a new locking block. A new gun? I'd look at either "centering" the existing new pin, or just drop in a different pin.

I recently noticed in the newest parts list that the latest revision of the LB pin (for other than 36, 42 & 43) now has a shiny finish, replacing the dull matte black finish. A little over 10 years ago I was told in one class that Glock had changed the heat treat on the LB pins, but it's not a surprise if they occasionally decide that a revision helps improve their product in one way or another.

Also, remember that many of the today's newest plastic guns are parts-is-parts guns, and it's still possible that a part or assembly might not drop in and work as well in one particular gun, as it might in other examples of the same gun. Tolerance stack can be a real thing. (FWIW, this was even the case when working on S&W 3rd gen pistols as an armorer, as sometimes you might come across a drop-in part that might not offer the expected normal functioning in one particular gun, but that same part might work just fine is other guns. That was one of the reasons armorers always bench and function-tested new parts in particular guns.)

 

2. Trigger Spring hook where it connects to the Trigger Bar is canted off to the left or right side, rubbing between Trigger Bar and the inside of the Trigger Mechanism Housing. The Trigger Spring hook should lie straight up and down in its groove at its Trigger Bar attachment point. (This issue occurs most often in Gen4 pistols and post-2010 Gen3 pistols, which have an improved TS attachment point on the Trigger Bar.)


- I may very well have done, or not done this when I installed the factory "Minus" connector in my 43. Somehow the trigger spring hook "unhooked" and the trigger would not reset. I can't really remember the details as it was two years ago, but what you describe may have just solved that mystery for me. I have the pistol partially disassembled already, awaiting a slide stop lever. I may reinstall that connector and make sure it is properly indexed this time around.
That little BUG really needs help with that heavy pull required to get it to finally break. I know the Gen. 5 and 43 have a different trigger spring, but what you posted here may also explain what caused one of the three failures I've had with this pistol. Thanks for the info, Mike-M.

 

Take your pick on any of the above comments, but those from Mike-M are installation type errors made by noobs, which is the horse in the barn, not the zebra (ie, the most likely).

There is a surface finish on these factory steel pins (ie paint). With repeated usage (removal and replacement) is is possible to start rubbing the paint off and reducing the diameter of the contact surface.

There is also a lesson here not to overdo the frame cleaning: removal and installation of the frame parts (ie "complete dissaembly" to the extreme). With enough wear an tear, these parts will start to change dimension and loosen. If installed correctly, I also like the simple DIY solution of painting some easily removed coating over the holes or pins to increase the contact friction (nail polish is a good and cheap tool-- not too hard, not too soft, just right)

 

The pin that’s circled starts to walk out while shooting. I’ve only had it to the range twice since I got it any ideas?

When my Glock 19 Gen 3 was new it walked during the first 50 rounds. I pushed it back and never had a problem since.