An odd Glock issue - slide ALWAYS locks back, even cycled by hand

[misanthropist]

I had my G20 out at the range on Friday and it began malfunctioning in an unusual way.

It locks back when cycled, regardless of anything.

Now the usual thing is to say, "operator error", but in this case I have ruled that out completely.

Not only does it lock back when fired, it locks back when cycled by hand, with the slide stop out of the frame.

In fact, I have stripped the frame of everything but the locking block, and it still does it.

As long as the barrel is in the slide and the locking block is in the frame, the slide locks back at full recoil. It will return forward if given a good smack.

About the only thing that looks out of place to me is that the tabs on the frame which stick up behind the locking block are a little high relative to the locking block - that is they stick up above the block itself, and the one on the right is a little chewed up. But I don't know if that's significant or not.

The only other information I can add is that the gun feels like it is "wedging" in to place. It's not so much that there is a part in the way that needs to be knocked out of place as that the slide is recoiling too far, say, and wedging the barrel into the locking block.

Does this ring any bells for anyone?

[TheSmiter1]

That's odd if it still does it with the slide stop lever removed. Usually that's the culprit of constant slide lock...

[sfguard]

Wow, I would bet that Glock would like to take a look at it. Give them a call

[Robb Jensen]

Improper assembly.

[misanthropist]

That's good news, but could you elaborate? I shot Aim Fast Hit Fast with this glock - well, at least day one was shot with this glock - and had no problems. It's had about another 500 - 700 rounds though it since then without issues, and the problem showed up mid-shoot on Friday.

So is something assembled incorrectly in the slide? The frame is stripped except for the locking block so it seems reasonable to conclude that the problem does not lie in the lower half.

[Robb Jensen]

That's good news, but could you elaborate? I shot Aim Fast Hit Fast with this glock - well, at least day one was shot with this glock - and had no problems. It's had about another 500 - 700 rounds though it since then without issues, and the problem showed up mid-shoot on Friday.

So is something assembled incorrectly in the slide? The frame is stripped except for the locking block so it seems reasonable to conclude that the problem does not lie in the lower half.

Have you or anyone else taken the gun apart beyond field stripping?

Frame pins go out of the frame in this order.
Locking block pin (small metal one)
Trigger housing pin (small plastic one)
Trigger pin (large metal one)

To keep from F'ing up the assembly frames should be assembled in this order.
1st pin in should be the locking block pin (small metal one)
Trigger housing pin (small plastic one)
Slide in the slide stop lever keeping the spring under the locking block pin
Then install the trigger pin (large metal one)

I remove all pins from shooters left to right. They can be pushed either way but prefer them in/out the right side of the gun.

[PRGGodfather]

Improper assembly.

Absolutely. Your slide lock lever spring is in the wrong position or may be broken.

The tail of the lever spring should be tucked under the top pin. This is a common mistake with some inexperienced folks who have stripped a Glock frame and reassembled it in what appears to be the correct configuration. If the tail of the spring is NOT tucked under the pin, what you speak of can happen rather easily. In fact, one of my friends was doing some kitchen table gunsmithing and had this happen to him -- and it was a simple enough to fix.

Just about any Glock armorer can take a look at this, and fix it for you -- unless there is something else wrong, too.

Just my $.02...

[dvdlpzus]

If you live near me in AZ I can help you out. I am not a smith but have extensive time on my Glocks.

[misanthropist]

Yes, I detail stripped the frame...but it was about 2000 rounds ago. I don't recall ever having stripped the slide on this gun but can't guarantee I never have; I have stripped a lot of guns over the years so it's possible I'm forgetting this one.

Assuming that this is the product of improper assembly, what mistake is likely to cause this malfunction?

[PRGGodfather]

It's entirely possible the tail end of the lever spring has slipped out of position, since its reassembly. If you tucked the tail under one of the pins, you probably would have remembered that.

Take a look at the frame and the top pin. The tail end of the lever spring should UNDERNEATH the top frame pin, assuming you have a three pin Glock. It's the pin right above the trigger pivot pin.

When it comes to the locking of the slide to the rear, the issue is generally caused by the bottom half of the gun -- not the slide.