Before we get started, below are the different types of connectors we will be talking about.
I have seen both of these issues multiple times from customers at my full time position.
Reason One: Dislodging the Trigger Spring from on Top of the Cruciform
FYSA: This is going to be only for the Gen 5 users as the trigger and connector assembly are different from the S style spring of previous Gens.
During cleaning operators will oftentimes use a nylon brush to clean the inside of their Glock. While this is a great way of removing carbon you have to be careful to not dislodge other things. Remember on the Beretta M9? Operators will sometimes lose their trigger spring during cleaning. This same thing can happen with the trigger spring assembly on the Glock Gen 5. This assembly now has a lip that seats on top of the cruciform on the trigger. If operators get a little overzealous when cleaning they can push that lip off of the cruciform easily. To reseat that piece you will need to totally disassemble the Glock and reassemble the trigger.
If you want to see for yourself how easy it is, strip the slide, at this time the gun should be fired which makes the spring easier to push off, then take a punch and gently push on that lip, this will then dislodge it. When reassembling it you will see that this assembly is a bit more simple than the previous gens to put back together. Just ensure that that lip is over the cruciform so you don’t have to do this all over again.
Steph Fact: My favorite cleaning tool ever is the nylon toothbrush that Brownells sells and is heavy within the military cleaning tools.
Reason Two: Broken Connector Spring
Specifically on the Gen 4 (the Gen 5 connector is different) platforms or the Standard “S” connector spring, the leg that is connecting the spring to the cruciform on the trigger can break. When working on this Glock before even noticing the broken spring, I was able to reset the trigger but it wasn’t consistent. Out of the four times after putting the Glock together and racking it, it would reset once out of the four times. That being said, it can be missed so just be sure to inspect for that leg properly attached to the cruciform on the trigger.
Two Reasons Why Your Factory Glock Trigger May Not Be Resetting is written by Steph Martz for gatdaily.com