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Old March 17, 2012, 02:04 PM   #1
irish52084
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Glock 20 FTF issues

So I sold a glock 20 recently and upon meeting with the seller the pistol was difficult to take apart. The guiderod and spring appeared to be slipping off the perch and catching when the slide is retracted. The buyer didn't seem too concerned, but today sent me a message saying he's having lots of FTF issues with the pistol.

Any ideas as to possible reasons for this? Why would the guidrod all of a sudden start slipping off the perch?

The pistol has both the stock guiderod assembly and an extra power steel spring as well. It also has the NY trigger mod that makes the trigger somewhat heavier, but more crisp. I don't know why either of these mods would all of a sudden cause FTF issues.
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Old March 17, 2012, 07:58 PM   #2
4V50 Gary
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I wonder if he reassembled it correctly (spring backwards - if that affects anything). It could be his ammo. Last, the firing pin channel may need cleaning.

If that extra power spring is too strong and the gun is slightly out of battery?
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Old March 17, 2012, 08:10 PM   #3
irish52084
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He said he swapped the guide rods out to see if it made a difference and it didn't. I'm thinking the slide stop spring may be to blame. I'm meeting him tomorrow to take a look at it and see if we can't get it running right for him. I feel bad it's not working properly. It has run just fine for me.
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Old March 17, 2012, 09:14 PM   #4
JohnKSa
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What kind of failure to feeds is he having? The round can hang up on the barrel hood, nosedive into the magazine or jam against the ramp.

When you say the guiderod is slipping off the perch, what do you mean, exactly? The guiderod will not stay exactly in the assembly notch after the slide is racked the first time. After the first slide rack the guiderod slips down slightly out of full engagement with the assembly notch but should still be in contact with the barrel after/during disassembly.

The way the gun is made, it's not (shouldn't be) possible for the guiderod to move down so far that it's not in contact with the barrel after disassembly. The only way that could happen is if the end of the guiderod is badly worn to the point that its circumference is much too small, if it's a guiderod with an end that's too small, or if the channel beneath the guiderod has been damaged so badly that there's extra clearance below the guiderod that allows it to move downward too far.

But there's another problem. With the gun assembled, the guiderod end is NEVER in contact with the barrel if everything is the proper dimensions. Instead, the bottom half of the end of the guiderod bears against the matching plastic shelf directly above the slide lock spring and directly in front of the slide lock. So even if end of the guiderod is somehow slipping down too far, it shouldn't be hanging anything up because the end of the guiderod not bearing against the barrel anyway. In fact, other than some incidental contact between the spring and the bottom of the barrel, the guiderod/spring assembly doesn't bear against the barrel at all except during disassembly/assembly.

Finally, the NY trigger spring can make it necessary to hold the trigger during disassembly. In other words, the difficulty during disassembly could be a normal consequence of having an NY trigger spring installed. To strip a Glock with an NY spring, follow the normal procedure, but while moving the slide forward off the frame, depress the trigger.
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Old March 18, 2012, 12:17 AM   #5
irish52084
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From what I got from talking to him on the phone, the jams are rounds stopping against the feed ramp or less often a stove pipe.

The movement of the guide rod is as you described. It just comes slightly out of the assembly notch. I didn't know that holding the trigger down while removing the slide made a difference with the NY trigger mod. Learn something new everyday.

I'm meeting up with him tomorrow afternoon to hopefully resolve this issue. He's a nice guy and has done a ton of buying, selling and trading on our local gun trade site. It's a good group of people and I just want to make sure he's getting a fair deal and so am I. I'm not gonna leave the guy with a poorly functioning glock.
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Old March 18, 2012, 08:34 AM   #6
JohnKSa
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Quote:
The movement of the guide rod is as you described. It just comes slightly out of the assembly notch.
That is perfectly normal behavior. The assembly notch is just there for assembly and the guiderod doesn't stay in that position for long once the gun is assembled. During normal use the guiderod drops down slightly--after the slide moves backward more than about a tenth of an inch after the first time after the gun has been assembled. If we think about how the barrel tilts down during the normal slide operation it makes sense that tilting action pushes the guiderod downward too since it's directly under the barrel. After it's been pushed down that first time, it stays down.
Quote:
...the jams are rounds stopping against the feed ramp or less often a stove pipe.
I hate to say it because it's such a cliche, but my best guess at a cause is a grip related issue. Especially since the gun works for you but not for him, and especially with the types of malfunctions you describe. Stovepipes being included in the symptoms makes it a classic case.
Quote:
I didn't know that holding the trigger down while removing the slide made a difference with the NY trigger mod.
The normal trigger spring pulls backward and upward on the trigger bar. The backward pull holds the trigger back against the connector ramp which (since the connector ramp angles downward) keeps the trigger bar from drifting up and possibly interfering with the striker. The NY spring pushes upward but applies no backward force on the trigger bar. That upward force can cause the trigger bar to move upward and with nothing to hold it back against the connector ramp it can drift forward and upward and catch on the striker. That prevents the slide from coming forward during the removal process. Squeezing the trigger applies the backward force required and allows the slide to be removed easily.
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Old March 18, 2012, 11:14 PM   #7
irish52084
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Got my hands on it today and couldn't get a malfunction. My guesses are either bad ammo batch, shooter induced malfunctions or the buyer got cold feet.
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Old March 18, 2012, 11:21 PM   #8
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Thanks for the update. I'd say those three options cover the bases.
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