Gen 4 barrel locks up differently


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GLOOB
December 19, 2010, 04:23 PM
I noticed something surprising the other day. The Gen 4 G19 lock up is different from the Gen 3's.

When you press down on the barrel hood of a Gen 3 gun, it moves downward about a tenth or an inch or so. (The slide does not need to move back for this to happen.) Let go, and the barrel pops back up.

On the Gen 4 G19, the breech locks up like a vault. If you press on it, you can get the entire slide to move up/down maybe a couple hundredths due to rail clearance, but the barrel does not move in relation to the slide, whatsoever.

I just thought that was curious. I have not yet tried swapping barrels between guns. Maybe I'll try that and see what gives.

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M1key
December 19, 2010, 04:33 PM
stiffer recoil springs...

GLOOB
December 19, 2010, 04:53 PM
Yeah, I thought of that. So I pressed really, really hard. 20 times harder than what it takes on the gen3. The barrel simply would not budge on the gen4, unless I simultaneously retracted the slide. The gen3 barrel hood depresses easily (G19, 27, 21 all the same), and the slide does not move in the process.

It's not less movement. It's no movement. It appears to me that Glock made an intentional change/improvement to the way the gun locks up.

M1key
December 19, 2010, 05:11 PM
Examine the barrel lugs, barrel hood, breech face, recoil spring assy and compare with the Gen3. They should be the same dimensions. The only difference should be the stiffer, double recoil springs.

Many folks are having trouble with some models of the gen4s and I suspect it may be a combo of weak US ammo (9mm) and tighter chamber dimensions (40SW) along with the stiffer recoil springs.

But this is speculation on my part, since I own gen2s and gen3s, and have only held the gen4 in 40 caliber.

This is new, I take it. Have you shot it much? Do you notice much difference when you shoot, compared to the gen3? If you have feed or eject problems, I think just shooting it awhile to loosen the springs a bit should fix it.

This wouldn't be the first time Glock has tried to "fix what ain't broke".


M

GLOOB
December 19, 2010, 07:33 PM
It belongs to a friend. I've shot is 3 times, now, putting over 200 rounds through it. I have consistently shot tighter groups with it versus my gen3, not that it means anything. Let's just say, I've had zero malfunctions with it and there's likely a gen4 G23 in my future.

There is definitely something different about how it locks up, and it appears to be a GOOD thing.

REAPER4206969
December 19, 2010, 08:00 PM
Glock has done nothing to the lock up. It's simple tolerance stacking.

GLOOB
December 19, 2010, 08:06 PM
Apparently Glockophiles* don't understand the concept of improvement upon perfection. :banghead:

I give up. Pick one up and see for yourself.

*possibly a phenomenon that is more widespread than just Glock users. E.g. Series 70 better than Series 80, MkII better than MkIII, so on down the line, and so it will always be.

REAPER4206969
December 19, 2010, 08:13 PM
I wouldn't call killing their reputation for rock solid out-of-box reliability "improvement."

GLOOB
December 19, 2010, 08:27 PM
:banghead:

REAPER4206969
December 19, 2010, 08:30 PM
Go play with your GEN3 and stop having impure thoughts.

bkhosken
December 19, 2010, 08:58 PM
I have heard from some competition shooter friends that the Gen 4's will not take any of the Gen 3 go-fast parts (extended slide release, mag catch, etc.etc.). The gen 4's are completely different, apparently, in many respects.

1911Tuner
December 20, 2010, 06:23 AM
It's not a change, and it's not an improvement. It means that the lower barrel lug isn't being solidly supported by the crosspiece that cams it up into engagement with the slide...due to either a mis-machined lug or a mislocated crosspiece.

GLOOB
December 20, 2010, 06:48 AM
To be clear, are you saying that all 3 of my stock Gen3 Glocks, all purchased new from reputable gun shops, coincidentally have a mismachined lug and/or a misplaced crosspiece? Your gen3 Glock doesn't do this? I'm not talking a few hundredths. The barrel can be pushed down a LOT. But it springs back up.

They are all less than 2 years old and well maintained. I don't see any wear or machine marks on the lugs or the locking block.

After a bit of googling, I found this post on another forum, dated 2007.

Glocks relative lack of accuracy has to do with the guns design. Next time you have a Glock in hand take your thumb and push down on the barrel hood. You will find that even with an after market barrel it will move significantly. As long as the barrel is capable of moving during full lock up or can lock up in a different position the gun won't ever come close to reaching its full accuracy potential. Try the same thing with a good 1911 and you will notice that the barrel will have zero play.

This person's experience with Glocks seems to match mine.

On my bud's gen4, OTOH, the barrel has zero play - apparently just like a good 1911.

1911Tuner
December 20, 2010, 08:23 AM
To be clear, are you saying that all 3 of my stock Gen3 Glocks, all purchased new from reputable gun shops, coincidentally have a mismachined lug and/or a misplaced crosspiece?

That's the way it seems. Gunshop owners...reputable or otherwise...rarely do a detailed inspection of their guns unless an obvious problem is brought to their attention.

Since the heart of the Glock is essentially the Colt-Browning tilt barrel, short recoil operated system...it works in exactly the same way. The barrel is cammed into the slide via contact between the lower lug and the crosspiece. In a 1911, it's the slidestop crosspin. In linkless systems like the Hi-Power and the Glock...it's a crossmember in the frame. The function is the same. If the barrel isn't solidly supported by that crossmember, it will drop when pushed, and...depending on a few other specs and dimensions...it may or may not spring back up when released.

It's possible that more than a few barrels slipped through the cracks, which would explain the reason that several guns have the same issue. Possible that more than a few frames with mislocated crossmembers slipped though before Glock discovered the problem and corrected it.

Whether barrel or frame...or a little of both...all it takes is worn tooling or a slipped jig or fixture, and by the time the problem is noted...several hundred or even several thousand parts may be inventoried.

The good news is that it won't really hurt anything because the upper barrel lug will be fully engaged when the gun fires. It may cause a little vertical stringing on target due to the barrel not returning precisely to the same place after every shot...most notably on the first round...and then shoot into a group for the remaining rounds in the magazine. Hard to say until you put it to the test.

M1key
December 20, 2010, 11:40 AM
^^^yikes. Hogwash.

We don't have a little 1911 bias, do we there bud. I have never seen or heard of the condition you are referring to in a Glock pistol. If you do, send the darn thing back. You have a seriously defective pistol.

I own a pile of Glocks in all calibers. Every one of them are accurate shooters. G21, G37, G17, G31, etc, etc are capable of 2 inches at 25 yards with the right ammo. Not bad for a out-of-the-box duty piece.

Sure, you can push down on the barrel hood and get movement. Does not matter or affect accuracy in the Glock.

Having owned and shot an equally large pile of 1911s over the years, I know the barrel lock-up is crucial for accuracy in the 1911. That's what you get with a 100 year old design. That's why 1911s cost so much to get 'em right. Don't assume the same is true of the Glock pistol.





M

1911Tuner
December 20, 2010, 01:19 PM
We don't have a little 1911 bias, do we there bud.

Nope. Just notin' the facts. That Glock has Browning's fingerprints all over it...most notably the way the barrel is cammed up and supported. That's right, lad. Your Glock functions the same way as a 100 year-old design that somebody else thought of. Ain't that a hoot?

Sure, you can push down on the barrel hood and get movement. Does not matter or affect accuracy in the Glock.

Never guaranteed that it would. I said that it could. It does in some guns, and doesn't in others. The fact stands that if the barrel isn't solidly supported vertically, it may not return to the same place between shots. That, whether it's a Glock or a High Power, or a Sig...or anything else that works on the Browning tilt barrel system.

gudel
December 20, 2010, 01:50 PM
it's just stiff recoil spring, brand new and all that. don't worry about it.

GLOOB
December 20, 2010, 01:54 PM
Hmmm. PT1911, I'm going to eat some crow, here. Looking closely at my gen3's, the slide retracts ever so slightly when I depress the barrel hood. If I hold the slide closed, the barrel hood does not depress. I take this to mean you are correct, sir.

1911Tuner
December 20, 2010, 02:10 PM
it's just stiff recoil spring, brand new and all that. don't worry about it.

The spring doesn't have anything to do with it, but I agree not to worry about it.

If I hold the slide closed, the barrel hood does not depress.

The reason that the slide moves backward when the barrel is pushed down is because as the barrel moves down, the camming surface "walks" backward on the crossbar and pushes the slide backward due to contact between barrel hood and breechface. Essentially, it's reversing the process by which it goes to battery with the slide pushing the barrel forward. As the barrel moves forward, it also moves up as the camming surface of the lower lug rides over the crossbar.

The linkless systems employ a double cam. One end moves the barrel up, and the other pulls the barrel down. The 1911 uses a cam to move it up and a link to pull it down. That's the only basic difference.

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